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arXiv · 1002.1334

Anisotropic phase diagram of the frustrated spin dimer compound Ba3Mn2O8

E. C. Samulon·K. A. Al-Hassanieh·Y. -J. Jo·M. C. Shapiro·L. Balicas·C. D. Batista·I. R. Fisher
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Abstract

Heat capacity and magnetic torque measurements are used to probe the anisotropic temperature-field phase diagram of the frustrated spin dimer compound Ba3Mn2O8 in the field range from 0T to 18T. For fields oriented along the c axis a single magnetically ordered phase is found in this field range, whereas for fields oriented along the a axis two distinct phases are observed. The present measurements reveal a surprising non-monotonic evolution of the phase diagram as the magnetic field is rotated in the [001]-[100] plane. The angle dependence of the critical field (Hc1) that marks the closing of the spin gap can be quantitatively accounted for using a minimal spin Hamiltonian comprising superexchange between nearest and next nearest Mn ions, the Zeeman energy and single ion anisotropy. This Hamiltonian also predicts a non-monotonic evolution of the transition between the two ordered states as the field is rotated in the a-c plane. However, the observed effect is found to be significantly larger in magnitude, implying that either this minimal spin Hamiltonian is incomplete or that the magnetically ordered states have a slightly different structure than previously proposed.

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E. C. Samulon, K. A. Al-Hassanieh, Y. -J. Jo, M. C. Shapiro, L. Balicas, C. D. Batista, I. R. Fisher. 2010-04-14. Anisotropic phase diagram of the frustrated spin dimer compound Ba3Mn2O8. https://doi.org/10.1103/physrevb.81.104421

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