Magnetic ordering transition in the spin-gap compound Sr$_2$Cu(BO$_3$)$_2$

ORAL

Abstract

Sr$_2$Cu(BO$_3$)$_2$ is a weakly coupled dimer compound with an accessible spin gap between the singlet ground state and the lowest triplet excited state. The critical field (H$_{c} \simeq 56T$) above which the compound magnetically orders is significantly smaller than the intradimer coupling (J$ \simeq 100K$), indicating triplet delocalisation due to the effect of interdimer exchange. Here, we present results of anisotropic high field magnetisation measurements that reveal the effects of Dzyaloshinskii-Moriya exchange interactions in determining the nature of the ordered state for H $>$ H$_c$. We also present results that demonstrate how chemical pressure (the substitution of Ba for Sr) can be used to tune the spin gap in this material.

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Authors

  • I. R. Fisher

    • Dept. of Applied Physics, Stanford University
    • Department of Applied Physics, Stanford University

  • Suchitra E. Sebastian

  • P. Tanedo

    • Dept. of Applied Physics, Stanford University

  • Paul Goddard

  • Marcelo Jaime

    • Los Alamos National Laboratory

  • Neil Harrison

    • NHMFL, Los Alamos National Laboratory

  • S.A. Zvyagin

    • NHMFL, Tallahassee