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Bridging frustrated-spin-chain and spin-ladder physics: Quasi-one-dimensional magnetism of BiCu2PO6

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posted on 2018-08-09, 08:31 authored by Alexander A. Tsirlin, Ioannis RousochatzakisIoannis Rousochatzakis, Deepa Kasinathan, Oleg Janson, Ramesh Nath, Franziska Weickert, Christoph Geibel, Andreas M. Lauchli, Helge Rosner
© 2010 The American Physical Society. We derive and investigate the microscopic model of the quantum magnet BiCu2PO6 using band-structure calculations, magnetic susceptibility and high-field magnetization measurements, as well as exact diagonalization (ED) and density-matrix renormalization group (DMRG) techniques. The resulting quasi-one-dimensional spin model is a two-leg antiferromagnetic ladder with frustrating next-nearest-neighbor couplings along the legs. The individual couplings are estimated from band-structure calculations and by fitting the magnetic susceptibility with theoretical predictions, obtained using full diagonalizations. The nearest-neighbor leg coupling J1, the rung coupling J4, and one of the next-nearest-neighbor couplings J2 amount to 120-150 K while the second next-nearest-neighbor coupling is J2 (J2 /2. The spin ladders do not match the structural chains, and although the next-nearest-neighbor interactions J2 and J2( have very similar superexchange pathways, they differ substantially in magnitude due to a tiny difference in the O-O distances and in the arrangement of nonmagnetic PO4 tetrahedra. An extensive ED study of the proposed model provides the low-energy excitation spectrum and shows that the system is in the strong rung coupling regime. The strong frustration by the next-nearest-neighbor couplings leads to a triplon branch with an incommensurate minimum. This is further corroborated by a strong-coupling expansion up to second order in the inter-rung coupling. Based on high-field magnetization measurements, we estimate the spin gap of (32 K and suggest the likely presence of antisymmetric Dzyaloshinskii-Moriya anisotropy and interladder coupling J3. We also provide a tentative description of the physics of BiCu2PO6 in magnetic field, in the light of the low-energy excitation spectra and numerical calculations based on ED and DMRG. In particular, we raise the possibility for a rich interplay between one- and two-component Luttinger liquid phases and a magnetization plateau at 1/2 of the saturation value.


A.T. was funded by Alexander von Humboldt Foundation. F.W. acknowledges the financial support under the project M.FE.A.CHPHSM of the Max-Planck Society. Part of this work has been supported by EuroMagNET II under the EC contract 228043.



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Physical Review B - Condensed Matter and Materials Physics






TSIRLIN, A.A. ... et al., 2010. Bridging frustrated-spin-chain and spin-ladder physics: Quasi-one-dimensional magnetism of BiCu2PO6. Physical Review B - Condensed Matter and Materials Physics, 82: 144426.


© American Physical Society (APS)


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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/

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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.82.144426






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