Effect of anion substitution onto structural and magnetic properties of chromium chalcogenides |
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| Authors: | Joseph Wontcheu Wolfgang Bensch Sergiy Mankovsky Svitlana Polesya Hubert Ebert |
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| Affiliation: | 1. Institute of Inorganic Chemistry, Christian-Albrechts-University Kiel, Max-Eyth-Str. 2, D-24118 Kiel, Germany;2. Department of Chemistry, LMU Munich, Butenandstr. 3-13, D-81377 Munich, Germany;3. Department of Chemistry, University of Montreal, 2900 Boulevard Edouard-Montpetit, Montreal, QC, H3T 1J4, Canada;1. Department of Physics and Astronomy, Nanoscale Science and Engineering Center, University of Georgia, Athens, GA 30602, USA;2. School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China;3. Science and Technology on Surface Physics and Chemistry Laboratory, P. O. Box 718-35, Mianyang 621907, China;1. Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang 621900, People’s Republic of China;2. Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2;3. Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China;1. School of Physics, Sun Yat-sen University, Guangzhou 510275, China;2. Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China;3. State Key Laboratory for Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, China;1. State Key Laboratory of Low-Dimensional Quantum Physics, and Department of Physics, Tsinghua University, Beijing, 100084, China;2. Collaborative Innovation Center of Quantum Matter, Beijing, 100084, China;3. Department of Physics, University of California, Davis, CA, 95616, USA;4. Department of Physics, University of New Hampshire, Durham, NH, 03824, USA;5. Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA |
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| Abstract: | We investigated experimentally and theoretically the effect of the substitution of Te by Se onto the structural, magnetic and electronic properties of ferromagnetic Cr5±xTe8 as parent material. Whereas Cr5Te8 is dimorphic crystallizing in a monoclinic and trigonal modification, Se substituted samples crystallize in two different trigonal modifications depending on the synthesis conditions. One of the modifications can be viewed as self-intercalated dichalcogenides Cr1+xQ2 (Q = Te, Se) and the other is a superstructure which is isostructural to one of the Cr5±xTe8 modifications. For the Se richest samples (Te:Se = 1:7) a new modification is identified which was formerly reported for Cr3+xSe4. For a distinct Cr content the replacement of Se by Te induces a reduction of the unit cell volumes, of the Cr-Cr and Cr-Te/Se distances. Increasing the Cr content for a constant Te:Se ratio has the opposite effect. The results also suggest that the homogeneity range extends to more Cr rich compounds with decreasing Te content. For a given Cr content the substitution of Te by Se weakens the ferromagnetic exchange interactions and strengthens the antiferromagnetic exchange. With increasing Cr content and a fixed Te:Se ratio ferromagnetic properties become more pronounced. The low temperature magnetic behavior is characterized by spin-glass, spin-glass like or cluster-glass properties depending on the Cr content and the Te:Se ratio. Electronic structure calculations done within the framework of LSDA (local spin density approximation) gave a detailed insight into the electronic and magnetic properties of the investigated systems supporting the interpretation of the achieved experimental results. This applies in particular for the calculated exchange coupling constants that provided the necessary input for Monte Carlo simulations used for theoretical investigations on the magnetic properties at finite temperatures. |
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