Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 42: Correlated Electrons: Frustrated Magnets - Cu-based Systems & FeCr
TT 42.4: Vortrag
Mittwoch, 9. März 2016, 10:15–10:30, H18
Spin model of volborthite Cu3V2O7(OH)2·2H2O revisited: coupled trimers instead of zigzag chains — •Oleg Janson1, Shunsuke Furukawa2, Tsutomu Momoi3, 4, Philippe Sindzingre5, Johannes Richter6, and Karsten Held1 — 1IFP, TU Wien, Austria — 2University of Tokyo, Japan — 3Condensed Matter Theory Laboratory, RIKEN, Japan — 4RIKEN Center for Emergent Material Science, Japan — 5Université Pierre & Marie Curie, Paris, France — 6University of Magdeburg, Germany
Motivated by recent experiments on volborthite single crystals showing a wide 1/3-magnetization plateau [1], we adopt the structural data and perform microscopic modeling by means of density functional theory (DFT). Using DFT+U, we find four leading magnetic exchanges: antiferromagnetic J and J2, as well as ferromagnetic J′ and J1. Simulations of the spin Hamiltonian show good agreement with the experiment for J:J′:J1:J2 = 1 : −0.2 : −0.5 : 0.2 with J ≃ 252 K. The 1/3-plateau phase pertains to polarized magnetic trimers formed by strong J bonds. An effective J→∞ model shows a tendency towards condensation of magnon bound states preceding the plateau phase [2].
[1] H. Ishikawa et al., PRL 114, 227202 (2015).
[2] O. Janson et al., arXiv:1509.07333.