Publications

Fabian von Rohr

Chimia 78 12, 855-861 (2024)

In this perspective, we will discuss the impact of some of the most recent advancements in materials discovery, particularly focusing on the role of robotics, artificial intelligence, and self-driving laboratories, as well as their implications for the Swiss research landscape. While it seems…

Xiaohanwen Lin, Fan Wu, Sara Almudena Lopez Paz, Fabian von Rohr, Marco Gibertini, Ignacio Gutierrez Lezama and Alberto Morpurgo

Physical review research 6 1, 013185 (2024)

We investigate the c -direction conduction in CrSBr in the linear regime, which is not accessible in other van der Waals (vdW) magnetic semiconductors, because of the unmeasurably low current. The resistivity, which is 10 8 − 10 11 times larger than in the a and b directions, exhibits magnetic…

Debarchan Das, KeYuan Ma, Jan Jaroszynski, Vahid Sazgari, Tomasz Klimczuk, Fabian von Rohr and Zurab Guguchia

Physical review. B 110 17, 174507 (2024)

Here we report muon spin rotation ( μ SR ) experiments on the temperature and field dependence of the effective magnetic penetration depth λ ( T ) in the η -carbide-type suboxide Ti 4 Ir 2 O , a superconductor with a considerably high upper critical field. The temperature dependence of λ ( T ) …

C. W. Nicholson, M. D. Watson, A. Pulkkinen, M. Rumo, G. Kremer, K. Y. Ma, Fabian von Rohr, C. Cacho and C. Monney

Physical review. B 110 20, 205123 (2024)

Competing interactions in low-dimensional materials can produce nearly degenerate electronic and structural phases. We investigate structural phase transitions in layered IrTe 2 for which a number of potential transition mechanisms have been postulated. The spatial coexistence of multiple phases…

S. Galeski, K. Araki, O. K. Forslund, R. Wawrzyńczak, H. F. Legg, P. K. Sivakumar, U. Miniotaite, F. Elson, M. Månsson, Catherine Witteveen, Fabian von Rohr, A. Q. R. Baron, D. Ishikawa, Q. Li, G. Gu, L. X. Zhao, W. L. Zhu, G. F. Chen, Y. Wang, S. S. P. Parkin, D. Grobunov, S. Zherlitsyn, B. Vlaar, D. H. Nguyen, S. Paschen, P. Narang, C. Felser, J. Wosnitza, T. Meng, Y. Sassa, S. A. Hartnoll and J. Gooth

Physical review. B 110 12, L121103 (2024)

The electron-phonon interaction is in many ways a solid state equivalent of quantum electrodynamics. Being always present, the e-p coupling is responsible for the intrinsic resistance of metals at finite temperatures, making it one of the most fundamental interactions present in solids. In typical…

Lifen Shi, Keyuan Ma, Binbin Ruan, Ningning Wang, Jun Hou, Pengfei Shan, Pengtao Yang, Jianping Sun, Genfu Chen, Zhian Ren, Fabian von Rohr, Bosen Wang and Jinguang Cheng

Physical review. B 110 21, 214520 (2024)

We revised normal-state and superconducting properties of an alloy superconductor N⁢b4⁢R⁢h2⁡C1−𝛿 through electrical transport, magnetic susceptibility, and specific heat. Our results reveal that it is a Pauli paramagnetic bad metal, a strongly coupled superconductor with specific heat…

Michael Straub, Francesco Petocchi, Catherine Witteveen, F. B. Kugler, Andrew Scott Hunter, Yann Alexanian, Gianmarco Gatti, Salony Mandloi, C. Polley, G. Carbone, J. Osiecki, Fabian von Rohr, Antoine Georges, Felix Baumberger and Anna Tamai

Preprint (2024)

We study the electronic structure of bulk 1T-TaSe$_2$ in the charge density wave phase at low temperature. Our spatially and angle resolved photoemission (ARPES) data show insulating areas coexisting with metallic regions characterized by a chiral Fermi surface and moderately correlated…

C. W. Nicholson, F. Petocchi, B. Salzmann, Catherine Witteveen, M. Rumo, G. Kremer, O. Ivashko, Fabian von Rohr, P. Werner and C. Monney

Physical review. B 109 3, 035167 (2024)

Ritu Gupta, Catherine Witteveen, Debarchan Das, Fabian von Rohr and Rustem Khasanov

Physical review. B 109 13, 134507 (2024)

We report on the microscopic superconducting properties of the Dirac semimetal PdTe2. In this study, we have focused on mosaic crystals of PdTe2, and used detailed zero-field and transverse-field muon-spin relaxation/rotation (μSR), ac-magnetic susceptibility, and resistivity measurements to…

Anastasiia Lukovkina, Sara Almudena Lopez Paz, Céline Besnard, Laure Guenee, Fabian von Rohr and Enrico Giannini

Chemistry of materials 36 12, 6237-6245 (2024)

The structurally related compounds NiI₂ and CoI₂ are multiferroic van der Waals materials in which helimagnetic orders exist simultaneously with electric polarization. Here, we report on the evolution of the crystal structure and of the magnetic properties across solid…

Robin Lefèvre, Félix Eder and Fabian von Rohr

Helvetica Chimica Acta 107 4, e202400018 (2024)

Through the application of synthesis via molten indium flux, we have been able to expand the ternary Sc−Mn−Si system and the quaternary Sc−Mn−Al−Si system. Specifically, we report on five previously unknown chemical compounds, namely β-ScMnSi2, Sc4+xMn4Si7–2x, Sc2Mn4Si5, Sc2Mn3Si4, and …

Danyang Liu, Jens Oppliger, Aleš Cahlík, Catherine Witteveen, Fabian von Rohr and Fabian Donat Natterer

MethodsX 10, 101964 (2023)

Elisabetta Nocerino, Shintaro Kobayashi, Catherine Witteveen, Ola K. Forslund, Nami Matsubara, Chiu Tang, Takeshi Matsukawa, Akinori Hoshikawa, Akihiro Koda, Kazuyoshi Yoshimura, Izumi Umegaki, Yasmine Sassa, Fabian von Rohr, Vladimir Pomjakushin, Jess H. Brewer, Jun Sugiyama and Martin Månsson

Communications materials 4 1, 81 (2023)

LiCrSe ₂ constitutes a recent valuable addition to the ensemble of two-dimensional triangular lattice antiferromagnets. In this work, we present a comprehensive study of the low temperature nuclear and magnetic structure established in this material. Being subject to a strong…

Catherine Witteveen, Elisabetta Nocerino, Sara Almudena Lopez Paz, Harald O Jeschke, Vladimir Y Pomjakushin, Martin Månsson and Fabian von Rohr

JPhys materials 6 3, 035001 (2023)

We report on the synthesis of LiCrTe 2 single crystals and on their anisotropic magnetic properties. We have obtained these single crystals by employing a Te/Li-flux synthesis method. We find LiCrTe 2 to crystallize in a TlCdS 2 -type structure with cell parameters of a = 3.9512(5) Å and c =…

Björn Salzmann, Elina Hujala, Catherine Witteveen, Baptiste Hildebrand, Helmuth Berger, Fabian von Rohr, Christopher W. Nicholson and Claude Monney

Physical review materials 7 6, 064005 (2023)

Dorota Iwona Walicka, Robin Lefèvre, Olivier Blacque, Sara Almudena Lopez Paz, Willem Rischau, Antonio Cervellino, Carlos A. Triana and Fabian von Rohr

Physical review materials 7 7, 074805 (2023)

Fengrui Yao, Volodymyr Multian, Zhe Wang, Nicolas Ubrig, Jérémie Teyssier, Fan Wu, Enrico Giannini, Marco Gibertini, Ignacio Gutierrez Lezama and Alberto Morpurgo

Nature communications 14 1, 4969 (2023)

In twisted two-dimensional (2D) magnets, the stacking dependence of the magnetic exchange interaction can lead to regions of ferromagnetic and antiferromagnetic interlayer order, separated by non-collinear, skyrmion-like spin textures. Recent experimental searches for these textures have focused on …

Fabian von Rohr

Chemistry of materials 35 22, 9455-9472 (2023)

The concept of topological superconductivity has attracted immense interest in the physics community recently for several reasons: First, topological superconductors represent new phases of matter, which are topologically distinct from any other known phase of matter. Second, their discovery would…

Giulia Tenasini, David Soler Delgado, Zhe Wang, Fengrui Yao, Dumitru Dumcenco, Enrico Giannini, Kenji Watanabe, Takashi Taniguchi, Christian Moulsdale, Aitor Garcia-Ruiz, Vladimir I. Fal’ko, Ignacio Gutierrez Lezama and Alberto Morpurgo

Nano letters 22 16, 6760-6766 (2022)

Dorota Pulmannova, Céline Besnard, Petr Bezdička, Marios Hadjimichael, Jérémie Teyssier and Enrico Giannini

CrystEngComm 24 20, 3731-3740 (2022)

We have grown single crystals of a new polymorph of Sr ₂ TiO ₄ . It contains titanium in an unusual tetrahedral coordination and transforms to the Ruddlesden–Popper structure with an interesting orientational relationship.

E. Nocerino, Catherine Witteveen, S. Kobayashi, O. K. Forslund, N. Matsubara, A. Zubayer, F. Mazza, S. Kawaguchi, A. Hoshikawa, I. Umegaki, J. Sugiyama, K. Yoshimura, Y. Sassa, Fabian von Rohr and M. Månsson

Scientific reports 12 1, 21657 (2022)

Two-dimensional (2D) triangular lattice antiferromagnets (2D-TLA) often manifest intriguing physical and technological properties, due to the strong interplay between lattice geometry and electronic properties. The recently synthesized 2-dimensional transition metal dichalcogenide LiCrTe $$_2$$ 2 , …

Manuele Danilo Balestra, Omargeldi Atanov, Robin Lefèvre, Olivier Blacque, Yat Hei Ng, Rolf Lortz and Fabian von Rohr

Journal of materials chemistry. C 10 32, 11703-11709 (2022)

We report on the discovery of Nb ₄ SiSb ₂ . This compound is a new superconductor with a T _c of 1.6 K. The channel void positions of this phase can be partly filled with Cu, Pd, or Pt, which leads to a lowering of the transition temperature.

Sara Almudena Lopez Paz and Fabian von Rohr

Chimia 76 7-8, 628-634 (2022)

Exploratory quantum materials discovery remains crucial to progress in material science. Due to the grand challenges that we are facing in predicting these materials and their properties from scratch, chemical design principles remain a key ingredient for the discovery of new materials. Chemical…

Sara Almudena Lopez Paz, Zurab Guguchia, Vladimir Y. Pomjakushin, Catherine Witteveen, Antonio Cervellino, Hubertus Luetkens, Nicola Casati, Alberto Morpurgo and Fabian von Rohr

Nature communications 13 1, 4745 (2022)

The van-der-Waals material CrSBr stands out as a promising two-dimensional magnet. Here, we report on its detailed magnetic and structural characteristics. We evidence that it undergoes a transition to an A-type antiferromagnetic state below T _N ≈ 140 K with a pronounced…

Casey K. W. Leung, Xiaofu Zhang, Fabian von Rohr, Rolf Lortz and Berthold Jäck

Scientific reports 12 1, 12773 (2022)

High-entropy alloys (HEA) form through the random arrangement of five or more chemical elements on a crystalline lattice. Despite the significant amount of resulting compositional disorder, a subset of HEAs enters a superconducting state below critical temperatures, $$T_{\text{c}}

Jens Oppliger, Berk Zengin, Danyang Liu, Kevin Hauser, Catherine Witteveen, Fabian von Rohr and Fabian Donat Natterer

MethodsX 9, 101784 (2022)

Xiaofu Zhang, Rui Shu, Huanlong Liu, Anna Elsukova, Per O. Å. Persson, Andreas Schilling, Fabian von Rohr and Per Eklund

Communications physics 5 1 (2022)

Superconducting high entropy alloys (HEAs) may combine extraordinary mechanical properties with robust superconductivity. They are suitable model systems for the investigation of the interplay of disorder and superconductivity. Here, we report on the superconductivity in (TaNb) _{1- x} …

Francesco Barantani, Michaël Tran, I. Madan, Itzik Kapon, Nimrod Bachar, T. c. Asmara, E. Paris, Y. Tseng, W. Zhang, Y. Hu, Enrico Giannini, G. Gu, T. p. Devereaux, Christophe Berthod, F. Carbone, T. Schmitt and Dirk Van Der Marel

Physical review. X 12 2, 021068 (2022)

Hai Lin, Dariusz Jakub Gawryluk, Yannick Maximilian Klein, Shangxiong Huangfu, Ekaterina Pomjakushina, Fabian von Rohr and Andreas Schilling

New journal of physics 24 1, 013022 (2022)

Motivated by the recent discovery of superconductivity in infinite-layer nickelate thin films, we report on a synthesis and magnetization study on bulk samples of the parent compounds RNiO₂ (R = La, Pr, Nd). The frequency-dependent peaks of the alternating current magnetic…

Robin Lefèvre and Fabian von Rohr

Chemistry of materials 34 5, 2352-2360 (2022)

We report on the hitherto unknown compound CeZn_2−δGe₂ (δ ≈ 0.41). We find that this compound crystallizes in a defect version of the well-known CaBe₂Ge₂ structure type. The phase forms in a Zn/In flux and with Zn deficiency on one of its…

Willem Rischau, Dorota Pulmannova, Gernot Scheerer, Adrien Stucky, Enrico Giannini and Dirk Van Der Marel

Physical Review Research 4 1, 013019 (2022)

Doped strontium titanate SrTiO3 (STO) is one of the most dilute superconductors known today. The fact that superconductivity occurs at very low carrier concentrations is one of the two reasons that the pairing mechanism is not yet understood, the other being the role played by the proximity to a…

Dorota Pulmannova

Thèse (2022)

Strontium titanate is a cubic perovskite, which is insulating in its pristine state but becomes metallic upon electron doping. It is one of the most dilute superconductors and the pairing mechanism is unknown. In addition, SrTiO₃ is a quantum paraelectric, in which zero-point…

David Soler Delgado, Fengrui Yao, Dumitru Dumcenco, Enrico Giannini, Jiaruo Li, Connor A. Occhialini, Riccardo Comin, Nicolas Ubrig and Alberto Morpurgo

Nano letters, 2c01361 (2022)

Fan Wu, Ignacio Gutierrez Lezama, Sara A. Lopéz‐Paz, Marco Gibertini, Kenji Watanabe, Takashi Taniguchi, Fabian Oliver Von Rohr, Nicolas Ubrig and Alberto Morpurgo

Advanced materials, 2109759 (2022)

We investigate electronic transport through exfoliated multilayers of CrSBr, a 2D semiconductor that is attracting attention because of its magnetic properties. We find an extremely pronounced anisotropy that manifests itself in qualitative and quantitative differences of all quantities measured…

M. Rumo, A. Pulkkinen, B. Salzmann, G. Kremer, B. Hildebrand, K. Y. Ma, Fabian von Rohr, C. W. Nicholson, T. Jaouen and C. Monney

Physical review materials 5 7, 074002 (2021)

We present a combined angle-resolved photoemission spectroscopy and low-energy electron diffraction (LEED) study of the prominent transition metal dichalcogenide IrTe₂ upon potassium (K) deposition on its surface. Pristine IrTe₂ undergoes a series of charge-ordered phase…

Christopher W. Nicholson, Maxime Rumo, Aki Pulkkinen, Geoffroy Kremer, Björn Salzmann, Marie-Laure Mottas, Baptiste Hildebrand, Thomas Jaouen, Timur K. Kim, Saumya Mukherjee, KeYuan Ma, Matthias Muntwiler, Fabian von Rohr, Cephise Cacho and Claude Monney

Communications materials 2 1, 25 (2021)

Strain is ubiquitous in solid-state materials, but despite its fundamental importance and technological relevance, leveraging externally applied strain to gain control over material properties is still in its infancy. In particular, strain control over the diverse phase transitions and topological…

KeYuan Ma, Karolina Gornicka, Robin Lefèvre, Yikai Yang, Henrik M. Rønnow, Harald O. Jeschke, Tomasz Klimczuk and Fabian von Rohr

ACS Materials Au 1 1, 55-61 (2021)

The upper critical field is a fundamental measure of the strength of superconductivity in a material. It is also a cornerstone for the realization of superconducting magnet applications. The critical field arises because of the Cooper pair breaking at a limiting field, which is due to the Pauli…

Lisa Grad, Fabian von Rohr, Matthias Hengsberger and Jürg Osterwalder

Physical review materials 5 7, 075401 (2021)

Antimony sulfide (Sb₂S₃) is a promising material for solar energy conversion. It consists of earth-abundant elements with a low toxicity and high stability. Furthermore, it shows suitable optical and electronic properties like a large absorption coefficient and a convenient…

G. Kremer, M. Rumo, C. Yue, A. Pulkkinen, C. W. Nicholson, T. Jaouen, Fabian von Rohr, P. Werner and C. Monney

Physical review. B 104 3, 035125 (2021)

Black phosphorus is a quasi-two-dimensional layered semiconductor with a narrow direct band gap of 0.3 eV. A giant surface Stark effect can be produced by the potassium doping of black phosphorus, leading to a semiconductor to semimetal phase transition originating from the creation of a strong…

Dorota Iwona Walicka, Zurab Guguchia, Jorge Lago, Olivier Blacque, KeYuan Ma, Huanlong Liu, Rustem Khasanov and Fabian von Rohr

Physical review research 3 3, 033192 (2021)

We report on the structural and microscopic superconducting properties of the Ca1−xSrxAlSi solid solution. Specifically, we have realized the continuous solid solution, which for all members, other than x=0 (CaAlSi), crystallizes in the AlB2-type structure. For CaAlSi, we present an improved…

KeYuan Ma, Robin Lefèvre, Qingtian Li, Jorge Lago, Olivier Blacque, Wanli Yang and Fabian von Rohr

Chemical science 12 41, 13870-13877 (2021)

Pyrite, also known as fool’s gold is the thermodynamic stable polymorph of FeS₂. It is widely considered as a promising d-band semiconductor for various applications due to its intriguing physical properties. Marcasite is the other naturally occurring polymorph of FeS₂….

KeYuan Ma, Robin Lefèvre, Karolina Gornicka, Harald O. Jeschke, Xiaofu Zhang, Zurab Guguchia, Tomasz Klimczuk and Fabian von Rohr

Chemistry of materials 33 22, 8722-8732 (2021)

Ti₂Ni and the related η-carbide structure are known to exhibit various intriguing physical properties. The Ti₂Ni structure with the cubic space group Fd3̅m is surprisingly complex, consisting of a unit cell with 96 metal atoms. The related η-carbide compounds correspond to…

Maxime Rumo, Aki Pulkkinen, KeYuan Ma, Fabian von Rohr, Matthias Muntwiler and Claude Monney

Journal of physics. Condensed matter 34 7, 075001 (2021)

IrTe₂ undergoes a series of charge-ordered phase transitions below room temperature that are characterized by the formation of stripes of Ir dimers of different periodicities. Full hemispherical x-ray photoelectron diffraction (XPD) experiments have been performed to investigate the…

Catherine Witteveen, Karolina Górnicka, Johan Chang, Martin Månsson, Tomasz Klimczuk and Fabian von Rohr

Dalton transactions 50 9, 3216-3223 (2021)

We report on the phase formation and the superconducting properties in the NbS₂ system. Specifically, we have performed a series of standardized solid-state syntheses in this system, which allow us to establish a comprehensive synthesis map for the formation of the two polytypes…

Andrea Amoretti, Martina Meinero, Daniel K. Brattan, Federico Caglieris, Enrico Giannini, Marco Affronte, Christian Hess, Bernd Buechner, Nicodemo Magnoli and Marina Putti

Physical review research 2 2, 023387 (2020)

High-temperature superconductors are strongly coupled systems which present a complicated phase diagram with many coexisting phases. This makes it difficult to understand the mechanism which generates their singular transport properties. Hydrodynamics, which mostly relies on the symmetries of the…

Lisa Grad, Fabian von Rohr, Jianzhou Zhao, Matthias Hengsberger and Jürg Osterwalder

Physical review materials 4 10, 105404 (2020)

Antimony selenide (Sb₂Se₃) consists of one-dimensional ribbons that are van der Waals bonded to each other. Due to its favorable optoelectronic properties, it is a promising material for solar energy conversion. Owing to its narrow direct band gap and its high absorption…

Xiaofu Zhang, Natascha Winter, Catherine Witteveen, Thomas Moehl, Yuan Xiao, Fabio Krogh, Andreas Schilling and Fabian von Rohr

Physical review research 2 1, 013375 (2020)

We report on the preparation and the physical properties of superconducting (TaNb)_1−x(ZrHfTi)_x high-entropy alloy films. The films were prepared by means of magnetron sputtering at room temperature, with x ranging from 0 to 1 with an average thickness of 600-950 nm. All…

D. Santos-Cottin, E. Martino, F. Le Mardelé, Catherine Witteveen, Fabian von Rohr, C. C. Homes, Z. Rukelj and Ana Akrap

Physical review materials 4 2, 021201 (2020)

Molybdenum ditelluride, MoTe₂, is a versatile material where the topological phase can be readily tuned by manipulating the associated structural phase transition. The fine details of the band structure of MoTe₂, key to understanding its topological properties, have proven…

Shangxiong Huangfu, Zurab Guguchia, Denis Cheptiakov, Xiaofu Zhang, Hubertus Luetkens, Dariusz Jakub Gawryluk, Tian Shang, Fabian von Rohr and Andreas Schilling

Physical review. B 102 5, 054423 (2020)

The nickelate Pr₄Ni₃O₈ features quasi-two-dimensional layers consisting of three stacked square-planar NiO₂ planes, in a similar way to the well-known cuprate superconductors. The mixed-valent nature of Ni and its metallic properties makes it a candidate…

Otto E. O. Zeman, Fabian von Rohr, Lukas Neudert and Wolfgang Schnick

Zeitschrift für anorganische und allgemeine Chemie 646 4, 228-233 (2020)

We report on the synthesis of the II-IV-N₂ semiconductors ZnSiN₂, MnSiN₂, and the Zn_1-xMn_xSiN₂ solid solutions by a one-step solid-state metathesis reaction. The successful syntheses were carried out by reacting the corresponding…

Zurab Guguchia, Antonio M. dos Santos, Fabian von Rohr, Jamie J. Molaison, Soham Banerjee, Daniel Rhodes, Jiaxin Yin, Rustem Khasanov, James Hone, Yasutomo J. Uemura, M. Zahid Hasan, Hubertus Luetkens, Emil S. Bozin and Alex Amato

Journal of the Physical Society of Japan 89 9, 094707 (2020)

We report the temperature and pressure (p_max ≃ 1.5 GPa) evolution of the crystal structure of the Weyl semimetal T_d-MoTe₂ by combination of neutron diffraction and the X-ray total scattering experiments. We find that the fundamental non-centrosymmetric structure…

M. Rumo, C. W. Nicholson, A. Pulkkinen, B. Hildebrand, G. Kremer, B. Salzmann, M.-L. Mottas, K. Y. Ma, E. L. Wong, M. K. L. Man, K. M. Dani, B. Barbiellini, M. Muntwiler, T. Jaouen, Fabian von Rohr and C. Monney

Physical review. B 101 23, 235120 (2020)

In the transition metal dichalcogenide IrTe₂, low-temperature charge-ordered phase transitions involving Ir dimers lead to the occurrence of stripe phases of different periodicities, and nearly degenerate energies. Bulk-sensitive measurements have shown that, upon cooling,…

Shangxiong Huangfu, Gawryluk Dariusz Jakub, Xiaofu Zhang, Olivier Blacque, Pascal Puphal, Ekaterina Pomjakushina, Fabian von Rohr and Andreas Schilling

Physical review. B 101 10, 104104 (2020)

As a member of the Ruddlesden-Popper Ln_n+1Ni_nO_3n+1series rare-earth-nickelates, Pr₄Ni₃O₁₀consists of infinite quasi-two-dimensional perovskite-like Ni-O based layers. Although a metal-to-metal phase transition at T_pt ≈…

M.-L. Mottas, T. Jaouen, B. Hildebrand, M. Rumo, F. Vanini, E. Razzoli, Enrico Giannini, Céline Barreteau, D. R. Bowler, C. Monney, H. Beck and P. Aebi

Physical review. B 99 15, 155103 (2019)

Pavel Naumov, Shangxiong Huangfu, Xianxin Wu, Andreas Schilling, Ronny Thomale, Claudia Felser, Sergey Medvedev, Harald O. Jeschke and Fabian von Rohr

Physical review. B 100 15, 155113 (2019)

We report on high-pressure p≤45 GPa resistivity measurements on the perovskite-related mixed-valent compound CsAuBr₃. The compounds high-pressure resistivity can be classified into three regions: For low pressures (p

Fabian von Rohr, Alice Ryser, Huiwen Ji, Karoline Stolze, Jing Tao, Jessica J. Frick, Greta R. Patzke and Robert J. Cava

Chemistry 25 8, 2082-2088 (2019)

We describe the previously unreported oxygen excess hexagonal antimony tungsten bronze with composition Sb_0.5W₃O₁₀, in the following denoted as h-Sb_xWO_3+2x with x=0.167, to demonstrate its analogy to classical A_xWO₃…

KeYuan Ma, Jorge Lago and Fabian von Rohr

Journal of alloys and compounds 796, 287-292 (2019)

We report on the synthesis and the superconductivity in Zr₄Rh₂O_x (x = 0.4, 0.5, 0.6, 0.7, 1.0). These compounds crystallize in the η-carbide structure, which is a filled version of the complex intermetallic Ti₂Ni structure. We find that in the system…

Lukas Muechler, Zurab Guguchia, Jean-Christophe Orain, Jürgen Nuss, Leslie M. Schoop, Ronny Thomale and Fabian von Rohr

APL materials 7 12, 121103 (2019)

Nodal-line semimetals are topologically nontrivial states of matter featuring band crossings along a closed curve, i.e., nodal-line, in momentum space. Through a detailed analysis of the electronic structure, we show, for the first time, that the normal state of the superconductor NaAlSi, with a…

Zurab Guguchia, Dariusz J. Gawryluk, Marta Brzezinska, Stepan S. Tsirkin, Rustem Khasanov, Ekaterina Pomjakushina, Fabian von Rohr, Joel A. T. Verezhak, M. Zahid Hasan, Titus Neupert, Hubertus Luetkens and Alex Amato

npj quantum materials 4 1, 50 (2019)

Recently, the transition metal dichalcogenide (TMD) system 2M-WS₂ has been identified as a Dirac semimetal exhibiting both superconductivity with the highest T_c ~ 8.5 K among all the TMD materials and topological surface states. Here we report on muon spin rotation…

Fabian von Rohr, J.-C. Orain, R. Khasanov, Catherine Witteveen, Z. Shermadini, A. Nikitin, J. Chang, A. R. Wieteska, A. N. Pasupathy, M. Z. Hasan, A. Amato, H. Luetkens, Y. J. Uemura and Z. Guguchia

Science advances 5 11, eaav8465 (2019)

We report on muon spin rotation experiments probing the magnetic penetration depth λ(T) in the layered superconductors in 2H-NbSe₂ and 4H-NbSe₂. The current results, along with our earlier findings on 1T′-MoTe₂ (Guguchia et al.), demonstrate that the superfluid…

Fabian von Rohr and Robert J. Cava

Physical review materials 2 3, 034801 (2018)

High-entropy alloys (HEAs) are a new class of materials constructed from multiple principal elements statistically arranged on simple crystallographic lattices. Due to the large amount of disorder present, they are excellent model systems for investigating the properties of materials intermediate…

Xianxin Wu, Harald O. Jeschke, Domenico Di Sante, Fabian von Rohr, Robert J. Cava and Ronny Thomale

Physical review materials 2 3, 034802 (2018)

Motivated by recent experiments, we investigate the pressure-dependent electronic structure and electron-phonon (e-ph) coupling for simple cubic phosphorus by performing first-principles calculations within the full potential linearized augmented plane-wave method. As a function of increasing…

Z. Guguchia, A. Kerelsky, D. Edelberg, S. Banerjee, Fabian von Rohr, D. Scullion, M. Augustin, M. Scully, D. A. Rhodes, Z. Shermadini, H. Luetkens, A. Shengelaya, C. Baines, E. Morenzoni, A. Amato, J. C. Hone, R. Khasanov, S. J. L. Billinge, E. Santos, A. N. Pasupathy and Y. J. Uemura

Science advances 4 12, eaat3672 (2018)

Transition metal dichalcogenides (TMDs) are interesting for understanding the fundamental physics of two-dimensional (2D) materials as well as for applications to many emerging technologies, including spin electronics. Here, we report the discovery of long-range magnetic order below T_M = …

I. Pletikosić, Fabian von Rohr, P. Pervan, P. k. Das, I. Vobornik, R. j. Cava and T. Valla

Physical review letters 120 15, 156403 (2018)

The success of black phosphorus in fast electronic and photonic devices is hindered by its rapid degradation in the presence of oxygen. Orthorhombic tin selenide is a representative of group IV-VI binary compounds that are robust and isoelectronic and share the same structure with black…

Karoline Stolze, Jing Tao, Fabian von Rohr, Tai Kong and Robert J. Cava

Chemistry of materials 30 3, 906-914 (2018)

We have synthesized previously unreported high-entropy alloys (HEAs) in the pentanary (ScZrNb)_1-x[RhPd]_x and hexanary (ScZrNbTa)_1-x[RhPd]_x systems. The materials have CsCl-type structures and mixed site occupancies. Both HEAs are type-II superconductors…

Karoline Stolze, Tai Kong, Fabian von Rohr and Robert J. Cava

Journal of solid state chemistry 263, 141-147 (2018)

We report on the discovery and the magnetic properties of CaCo₄(TeO₃)₄Cl₂. Single-crystal X-ray diffraction shows that this compound crystallizes on a monoclinic lattice, in the space group C2/c with a = 19.869(1) Å, b = 5.323(1) Å, c = 16.965(1)…

Z. Guguchia, T. Adachi, Z. Shermadini, T. Ohgi, J. Chang, E. S. Bozin, Fabian von Rohr, A. M. dos Santos, J. J. Molaison, R. Boehler, Y. Koike, A. R. Wieteska, B. A. Frandsen, E. Morenzoni, A. Amato, S. J. L. Billinge, Y. J. Uemura and R. Khasanov

Physical review. B 96 9, 094515 (2017)

High-pressure neutron powder diffraction, muon-spin rotation, and magnetization studies of the structural, magnetic, and the superconducting properties of the Ce-underdoped superconducting (SC) electron-doped cuprate system with the Nd₂CuO₄ (the so-called T′) structure…

Jing Guo, Honghong Wang, Fabian von Rohr, Wei Yi, Yazhou Zhou, Zhe Wang, Shu Cai, Shan Zhang, Xiaodong Li, Yanchun Li, Jing Liu, Ke Yang, Aiguo Li, Sheng Jiang, Qi Wu, Tao Xiang, Robert J. Cava and Liling Sun

Physical review. B 96 22, 224513 (2017)

Here we report the in situ high-pressure (up to ∼50-GPa) Hall-effect measurements on single-crystal black phosphorus. We find a strong correlation between the sign of the Hall coefficient, an indicator of the dominant carrier type, and the superconducting transition temperature (T_c)….

Z. Guguchia, Fabian von Rohr, Z. Shermadini, A. T. Lee, S. Banerjee, A. R. Wieteska, C. A. Marianetti, B. A. Frandsen, H. Luetkens, Z. Gong, S. C. Cheung, C. Baines, A. Shengelaya, G. Taniashvili, A. N. Pasupathy, E. Morenzoni, S. J. L. Billinge, A. Amato, R. J. Cava, R. Khasanov and Y. J. Uemura

Nature communications 8 1, 1082 (2017)

In its orthorhombic T_d polymorph, MoTe₂ is a type-II Weyl semimetal, where the Weyl fermions emerge at the boundary between electron and hole pockets. Non-saturating magnetoresistance and superconductivity were also observed in T_d-MoTe₂. Understanding the …

Jing Guo, Honghong Wang, Fabian von Rohr, Zhe Wang, Shu Cai, Yazhou Zhou, Ke Yang, Aiguo Li, Sheng Jiang, Qi Wu, Robert J. Cava and Liling Sun

Proceedings of the National Academy of Sciences of the United States of America 114 50, 13144-13147 (2017)

We report the observation of extraordinarily robust zero-resistance superconductivity in the pressurized (TaNb)_0.67(HfZrTi)_0.33 high-entropy alloy–a material with a body-centered-cubic crystal structure made from five randomly distributed transition-metal elements. The…

Elizabeth M. Carnicom, Tomasz Klimczuk, Fabian von Rohr, Michal J. Winiarski, Tai Kong, Karoline Stolze, Weiwei Xie, Satya K. Kushwaha and Robert J. Cava

Journal of the Physical Society of Japan 86 8, 084710 (2017)

The growth and characterization of CePtIn₄, stabilized by 10% Zn substitution for In, is reported. The new material is orthorhombic, space group Cmcm (No. 63), with lattice parameters a = 4.51751(4) Å, b = 16.7570(2) Å, and c = 7.36682(8) Å, and the refined crystal composition has 10% …

M. Bendele, Fabian von Rohr, Z. Guguchia, E. Pomjakushina, K. Conder, A. Bianconi, A. Simon, A. Bussmann-Holder and H. Keller

Physical review. B 95 1, 014514 (2017)

The oxygen isotope (¹⁶O/¹⁸O) effect (OIE) on the pseudogap (charge-stripe ordering) temperature T* is investigated for the cuprate superconductor La_2−xSr_xCuO₄ as a function of doping x by means of x-ray absorption near edge structure studies. …

Fabian von Rohr, Huiwen Ji, F. Alexandre Cevallos, Tong Gao, N. Phuan Ong and Robert J. Cava

Journal of the American Chemical Society 139 7, 2771-2777 (2017)

Two-dimensional materials have significant potential for the development of new devices. Here we report the electronic and structural properties of β-GeSe, a previously unreported polymorph of GeSe, with a unique crystal structure that displays strong two-dimensional structural features. β-GeSe…

Henrik Grundmann, Alsu Sabitova, Andreas Schilling, Fabian von Rohr, Tobias Förster and Laurens Peters

New journal of physics 18 3, 033001 (2016)

The structure and magnetic interactions of the triplon Bose-Einstein condensation candidates Ba₃Cr₂O₈ and Sr₃Cr₂O₈ have been studied thoroughly in the literature, but little is known about a possible triplon condensation in the…

Fabian von Rohr, Anna Krzton-Maziopa, Vladimir Pomjakushin, Henrik Grundmann, Zurab Guguchia, Wolfgang Schnick and Andreas Schilling

Journal of physics. Condensed matter 28 27, 276001 (2016)

We report on the magnetic properties of CsCo₂Se₂ with ThCr₂Si₂ structure, which we have characterized through a series of magnetization and neutron diffraction measurements. We find that CsCo₂Se₂ undergoes a phase transition to an…

Z. Guguchia, R. Khasanov, Z. Bukowski, Fabian von Rohr, M. Medarde, P. K. Biswas, H. Luetkens, A. Amato and E. Morenzoni

Physical review. B 93 9, 094513 (2016)

We report muon spin rotation experiments on the magnetic penetration depth λ and the temperature dependence of λ⁻² in the over-doped Fe-based high-temperature superconductor (Fe-HTS) Ba_1−xRb_xFe₂As₂(x = 0.65) studied at ambient and under…

Fabian von Rohr, Michał J. Winiarski, Jing Tao, Tomasz Klimczuk and Robert Joseph Cava

Proceedings of the National Academy of Sciences of the United States of America 113 46, E7144-E7150 (2016)

High-entropy alloys are a new class of materials that consist of several principal elements arranged on simple lattices. These structures are stabilized by the high configurational entropy of the random mixing of the elements. Here, we show that the properties of a superconducting high-entropy…

E. Joliat, S. Schnidrig, B. Probst, C. Bachmann, B. Spingler, K. K. Baldridge, Fabian von Rohr, A. Schilling and R. Alberto

Dalton transactions 45 4, 1737-1745 (2016)

Complexes with purely pyridine-based macrocycles are rarely studied in photo(electro)catalysis. We synthesized and investigated macrocycles, in which two 2,2′-bipyridine (bpy) units are linked twice by two cyano-methylene groups, to yield the basic tetradentate, bipyridine based ligand framework…

Z. Guguchia, A. Amato, J. Kang, H. Luetkens, P. K. Biswas, G. Prando, Fabian von Rohr, Z. Bukowski, A. Shengelaya, H. Keller, E. Morenzoni, Rafael M. Fernandes and R. Khasanov

Nature communications 6, 8863 (2015)

The superconducting gap structure in iron-based high-temperature superconductors (Fe-HTSs) is non-universal. In contrast to other unconventional superconductors, in the Fe-HTSs both d-wave and extended s-wave pairing symmetries are close in energy. Probing the proximity between these very different …

Mazhar N. Ali, Fabian von Rohr, C. Campana, Andreas Schilling and R.j. Cava

Materials research bulletin 70, 673-677 (2015)

Crystals of NaPd₃X₂, (X = Si, Ge, Sn) were synthesized and their crystal structures investigated by single crystal X-ray diffraction. The previously reported structures of NaPd₃Si₂ and NaPd₃Sn₂ were confirmed….

Fabian von Rohr, Reinhard Nesper and Andreas Schilling

Physical review. B, Condensed matter and materials physics 89 9, 094505 (2014)

We report on the synthesis and the physical properties of Ba_1−xRb_xTi₂Sb₂O (x≤0.4) by x-ray diffraction, superconducting quantum interference device magnetometry, resistivity, and specific-heat measurements. Upon hole doping by substituting Ba with Rb, …

P. K. Biswas, Z. Salman, T. Neupert, E. Morenzoni, E. Pomjakushina, Fabian von Rohr, K. Conder, G. Balakrishnan, M. Ciomaga Hatnean, M. R. Lees, D. McK. Paul, A. Schilling, C. Baines, H. Luetkens, R. Khasanov and A. Amato

Physical review. B, Condensed matter and materials physics 89 16, 161107 (2014)

We present the results of a systematic investigation of the magnetic properties of the three-dimensional Kondo topological insulator SmB₆ using magnetization and muon-spin relaxation/rotation (μSR) measurements. The μSR measurements exhibit magnetic field fluctuations in…

M. Bendele, Z. Guguchia, Fabian von Rohr, T. Irifune, T. Shinmei, I. Kantor, S. Pascarelli, B. Joseph and C. Marini

Physical review. B, Condensed matter and materials physics 90 17, 174505 (2014)

The pressure dependence of the superconducting transition temperature Tc, the local structure, and the electronic properties of the iron chalcogenide superconductor FeSe_0.5Te_0.5 was investigated by means of SQUID magnetometry and site-selective polarized x-ray absorption…

Fabian von Rohr, Huixia Luo, Ni Ni, Michael Wörle and Robert J. Cava

Physical review. B, Condensed matter and materials physics 89 22, 224504 (2014)

We report the structure and the elementary physical properties of Ca₃Ir₄Ge₄. This compound crystallizes in the cubic, noncentrosymmetric Na₃Pt₄Ge₄ structure type with the space group I¯43m and the unit cell dimension a=7.56895(4)…

Maksym Yarema, Michael Wörle, Marta D. Rossell, Rolf Erni, Riccarda Caputo, Loredana Protesescu, Kostiantyn V. Kravchyk, Dmitry N. Dirin, Karla Lienau, Fabian von Rohr, Andreas Schilling, Maarten Nachtegaal and Maksym V. Kovalenko

Journal of the American Chemical Society 136 35, 12422-12430 (2014)

We report a facile colloidal synthesis of gallium (Ga) nanoparticles with the mean size tunable in the range of 12-46 nm and with excellent size distribution as small as 7-8%. When stored under ambient conditions, Ga nanoparticles remain stable for months due to the formation of native and…

Stefan Muff, Fabian von Rohr, Gabriel Landolt, Bartosz Slomski, Andreas Schilling, Robert J. Cava, Jürg Osterwalder and J. Hugo Dil

Physical review. B, Condensed matter and materials physics 88 3, 035407 (2013)

We identify the multilayered compound GeBi₄Te₇ to be a topological insulator with a Dirac point slightly above the valence band maximum, using angle-resolved photoemission spectroscopy (ARPES) measurements. The spin polarization satisfies the time reversal symmetry of the…

Fabian von Rohr, Andreas Schilling, Reinhard Nesper, Chris Baines and Markus Bendele

Physical review. B, Condensed matter and materials physics 88 14, 140501 (2013)

We have investigated the low-temperature physical properties of BaTi₂Sb₂O andBa_1−xNa_xTi₂Sb₂O (x = 0.05, 0.1, 0.15, 0.2, 0.25, 0.3) by means of muon spin rotation (μSR) and SQUID magnetometry. Our measurements reveal the absence of …

Fabian von Rohr, Andreas Schilling and Robert J Cava

Journal of physics. Condensed matter 25 7, 075804 (2013)

The thermoelectric properties between 10 and 300 K and the growth of single crystals of n-type and p-type GeBi₄Te₇, GeSb₄Te₇ and Ge(Bi_1−xSb_x)₄Te₇ solid solution are reported. Single crystals were grown by the…

S. Weyeneth, M. Bendele, Fabian von Rohr, P. Dluzewski, R. Puzniak, A. Krzton-Maziopa, S. Bosma, Z. Guguchia, R. Khasanov, Z. Shermadini, A. Amato, E. Pomjakushina, K. Conder, A. Schilling and H. Keller

Physical review. B, Condensed matter and materials physics 86 13, 134530 (2012)

An extended study of the superconducting and normal-state properties of various as-grown and post-annealed Rb_xFe_2−ySe₂ single crystals is presented. Magnetization experiments evidence that annealing of Rb_xFe_2−ySe₂ at 413 K, well…

Daigorou Hirai, Fabian von Rohr and R. J. Cava

Physical review. B, Condensed matter and materials physics 86 10, 100505 (2012)

The physical properties and structural evolution of the 122-type solid solution BaNi₂(Ge_1−xP_x)₂ are reported. The in-plane X-X (X = Ge_1−xP_x) dimer formation present in the end member BaNi₂Ge₂, which results…

A. Krzton-Maziopa, E.V. Pomjakushina, V.Yu. Pomjakushin, Fabian von Rohr, A. Schilling and K. Conder

Journal of physics. Condensed matter 24 38, 382202 (2012)

We report on a new iron selenide superconductor with a T_c onset of 45 K and the nominal composition Li_x(C₅H₅N)_yFe_2−zSe₂, synthesized via intercalation of dissolved alkaline metal in anhydrous pyridine at room…

Michael Wörle, Daniel Widmer, Fabian von Rohr, Frank Krumeich, Christian Mensing and Reinhard Nesper

Zeitschrift für anorganische und allgemeine Chemie 636 8, 1447-1453 (2010)

Ca_1-xB₂C₄ (x ~ 0.08) and Ca_1-xB₂C₆ (x ~ 0.04) are two compounds containing heterographene-B,C nets which were prepared by solid state synthesis and structurally characterized by X-ray powder diffraction data. Both compounds…