Electron spin resonance and exchange paths in the orthorhombic dimer system Sr2VO4

Joachim Deisenhofer (1) , S. Schaile (1) , Jeremie Teyssier (2) , Zhe Wang (1) , M. Hemmida (1) , H.-A. Krug von Nidda (1) , R. M. Eremina (3) , M. V. Eremin (4) , Romain Viennois (2, 5) , E. Giannini (2) , A. Loidl (1) , Dirk van Der Marel (2)

1 Experimentalphysik V, Center for Electronic Correlations and Magnetism, Institute for Physics
2 UNIGE - Université de Genève = University of Geneva
3 E. K. Zavoisky Physical Technical Institute
4 IoP - Institute of Physics [Kazan]
5 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier

We report on susceptibility and electron spin resonance (ESR) measurements at X- and Q-band frequencies of Sr2VO4 with orthorhombic symmetry. In this dimer system, the V4+ ions are in tetrahedral environment and are coupled by an antiferromagnetic intradimer 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 Hückel 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 fitted by a single Lorentzian line and the temperature dependence of the ESR intensity, and the dc susceptibility can be modeled by using the Bleaney-Bowers approach for independent dimers. The temperature dependence of the ESR linewidth at X-band frequency 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.

Domaines: Electrons fortement corrélés [cond-mat.str-el]

Joachim Deisenhofer, S. Schaile, Jeremie Teyssier, Zhe Wang, M. Hemmida, et al.. Electron spin resonance and exchange paths in the orthorhombic dimer system Sr2VO4. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2012, 86, pp.214417. ⟨10.1103/PhysRevB.86.214417⟩. ⟨hal-00770150⟩