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Decorated Shastry-Sutherland lattice in the spin- 1/2 magnet CdCu2(BO3)2

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posted on 07.08.2018, 13:16 authored by Oleg Janson, Ioannis RousochatzakisIoannis Rousochatzakis, Alexander A. Tsirlin, Johannes Richter, Yu Skourski, Helge Rosner
We report the microscopic magnetic model for the spin-1/2 Heisenberg system CdCu 2(BO 3) 2, one of the few quantum magnets showing the 1/2-magnetization plateau. Recent neutron diffraction experiments on this compound evidenced long-range magnetic order, inconsistent with the previously suggested phenomenological magnetic model of isolated dimers and spin chains. Based on extensive density functional theory band structure calculations, exact diagonalizations, quantum Monte Carlo simulations, third-order perturbation theory as well as high-field magnetization measurements, we find that the magnetic properties of CdCu 2(BO 3) 2 are accounted for by a frustrated quasi-2D magnetic model featuring four inequivalent exchange couplings: the leading antiferromagnetic coupling J d within the structural Cu 2O 6 dimers, two interdimer couplings J t1 and J t2, forming magnetic tetramers, and a ferromagnetic coupling J it between the tetramers. Based on comparison to the experimental data, we evaluate the ratios of the leading couplings J d:J t1:J t2:J it=1:0.20:0.45:-0.30, with J d of about 178K. The inequivalence of J t1 and J t2 largely lifts the frustration and triggers long-range antiferromagnetic ordering. The proposed model accounts correctly for the different magnetic moments localized on structurally inequivalent Cu atoms in the ground-state magnetic configuration. We extensively analyze the magnetic properties of this model, including a detailed description of the magnetically ordered ground state and its evolution in magnetic field with particular emphasis on the 1/2-magnetization plateau. Our results establish remarkable analogies to the Shastry-Sutherland model of SrCu 2(BO 3) 2, and characterize the closely related CdCu 2(BO 3) 2 as a material realization for the spin-1/2 decorated anisotropic Shastry-Sutherland lattice. © 2012 American Physical Society.

Funding

A. A. T. acknowledges the funding from Alexander von Humboldt Foundation.

History

School

  • Science

Department

  • Physics

Published in

Physical Review B - Condensed Matter and Materials Physics

Volume

85

Issue

6

Citation

JANSON, O. ... et al., 2012. Decorated Shastry-Sutherland lattice in the spin-1/2 magnet CdCu2(BO3)2. Physical Review B - Condensed Matter and Materials Physics, 85: 064404.

Publisher

© American Physical Society (APS)

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2012

Notes

This paper was accepted for publication in the journal Physical Review B - Condensed Matter and Materials Physics and the definitive published version is available at https://doi.org/10.1103/PhysRevB.85.064404

ISSN

1098-0121

eISSN

1550-235X

Language

en

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