We report on magnetization and electron spin resonance (ESR) measurements of Sr2VO4 with orthorhombic symmetry. In this dimer system the V4+ ions are in tetrahedral environment and are coupled by an antiferromagnetic intra-dimer exchange constant J/kB≈ 100 K to form a singlet ground state without any phase transitions between room temperature and 2 K. Based on an extended-H\"{u}ckel-Tight-Binding analysis we identify the strongest exchange interaction to occur between two inequivalent vanadium sites via two intermediate oxygen ions. The ESR absorption spectra can be well described by a single Lorentzian line with an effective g-factor g = 1.89. The temperature dependence of the ESR intensity is well described by a dimer model in agreement with the magnetization data. The temperature dependence of the ESR linewidth can be modeled by a superposition of a linear increase with temperature with a slope α = 1.35 Oe/K and a thermally activated behavior with an activation energy Δ/kB = 1418 K, both of which point to spin-phonon coupling as the dominant relaxation mechanism in this compound.
@article{arxiv.1210.1349,
title = {Electron spin resonance and exchange paths in the orthorhombic dimer system Sr2VO4},
author = {J. Deisenhofer and S. Schaile and J. Teyssier and Zhe Wang and M. Hemmida and H. -A. Krug von Nidda and R. M. Eremina and M. V. Eremin and R. Viennois and E. Giannini and D. van der Marel and A. Loidl},
journal= {arXiv preprint arXiv:1210.1349},
year = {2013}
}