MAGNETIC PHASE-DIAGRAM OF RBMNBR3, INVESTIGATED BY SPECIFIC-HEAT AND MAGNETOCALORIC EFFECT

We report on high-resolution measurements of the specific heat and mag netocaloric effect of the distorted triangular lattice antiferromagnet RbMnBr3. Zero-field specific-heat data show a clear anomaly at T-cl = 8.54 K and a second shoulderlike anomaly about 35 mK above the first one. We study the evolution of these anomalies in applied external fie lds along the c axis and in the basal plane. We present a detailed mag netic phase diagram for B perpendicular to c for fields up to 7 T whic h is compared with earlier neutron scattering results and theoretical work. [S0163-1829(98)06938-0].