Impact of strong disorder on the static magnetic properties of the spin-chain compound BaCu2SiGeO7

T. Shiroka, F. Casola, W. Lorenz, K. Prša, A. Zheludev, H.-R. Ott, and J. Mesot
Phys. Rev. B 88, 054422 – Published 26 August 2013

Abstract

The disordered quasi-one-dimensional magnet BaCu2SiGeO7 is considered as one of the best physical realizations of the random Heisenberg chain model, which features an irregular distribution of the exchange parameters and whose ground state is predicted to be the scarcely investigated random-singlet state (RSS). Based on extensive 29Si NMR and magnetization studies of BaCu2SiGeO7, combined with numerical quantum Monte Carlo simulations, we obtain remarkable quantitative agreement with theoretical predictions of the random Heisenberg chain model and strong indications for the formation of a random-singlet state at low temperatures in this compound. As a local probe, NMR is a well-adapted technique for studying the magnetism of disordered systems. In this case, it also reveals an additional local transverse staggered field, which affects the low-temperature properties of the RSS. The proposed model Hamiltonian satisfactorily accounts for the temperature dependence of the NMR line shapes.

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  • Received 10 July 2013

DOI:https://doi.org/10.1103/PhysRevB.88.054422

©2013 American Physical Society

Authors & Affiliations

T. Shiroka1,2, F. Casola1,2,*, W. Lorenz3, K. Prša4, A. Zheludev3, H.-R. Ott1,2, and J. Mesot1,2

  • 1Laboratorium für Festkörperphysik, ETH Hönggerberg, CH-8093 Zürich, Switzerland
  • 2Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
  • 3Neutron Scattering and Magnetism, Laboratorium für Festkörperphysik, ETH Hönggerberg, CH-8093 Zürich, Switzerland
  • 4Institute of Condensed Matter Physics, EPFL, CH-1015 Lausanne, Switzerland

  • *fr.casola@gmail.com

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Issue

Vol. 88, Iss. 5 — 1 August 2013

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