Surface and bulk magnetic properties of a layered transition metal compound BaMn₂Sb₂

Layered transition metal compounds have garnered attention due to their extremely rich physical properties. We present magnetic, thermal transport, and optical properties of BaMn₂Sb₂ single crystals with the I4/mmm structure. In addition to the G-type antiferromagnetic (AFM) ordering at 441 K, the slope of the c-axis magnetic susceptibility changes sign below T_x ~80 K. Correspondingly, the thermal conductivity is suppressed below T_x when measured under the application of a 14-Tesla magnetic field. While the second harmonic generation (SHG) measurements reveal the expected C₄ surface symmetry, the polarization intensity tends to decrease with decreasing temperature below T_x. Possible origin for the observed anomalies at T_x will be discussed.