2012/12/18 by V. Kocsis, Vilmos Kocsis, S. Bordács +11 · 3 citations
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Atomic orbital #Chemistry #Condensed matter physics #Crystal structure #Crystallography #Ion #Magnetic and transport properties of perovskites and related materials #Materials science #Multiferroics and related materials #Octahedron #Physics #Quantum mechanics #Spinel #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.87.064416
published as Phys. Rev. B 87, 064416 (2013) · 10 pages, 11 figures
arxiv created 2012/12/18 · openalex publication_date 2013/02/20 · arxiv updated 2013/07/24 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Dynamical properties of the lattice structure were studied by optical spectroscopy in ACr2O4 chromium spinel oxide magnetic semiconductors over a broad temperature region of T=10--335 K. The systematic change of the A-site ions (A= Mn, Fe, Co, Ni and Cu) showed that the occupancy of 3d orbitals on the A site has strong impact on the lattice dynamics. For compounds with orbital degeneracy (FeCr2O4, NiCr2O4, and CuCr2O4), clear splitting of infrared-active phonon modes and/or activation of silent vibrational modes have been observed upon the Jahn-Teller transition and at the onset of the subsequent long-range magnetic order. Although MnCr2O4 and CoCr2O4 show multiferroic and magnetoelectric character, no considerable magnetoelasticity was found in spinel compounds without orbital degeneracy as they closely preserve the high-temperature cubic spinel structure even in their magnetic ground state. Aside from lattice vibrations, intra-atomic 3d-3d transitions of the A2+ ions were also investigated to determine the crystal field and Racah parameters and the strength of the spin-orbit coupling.