Unusual magnetic, thermal, and transport behavior of single-crystalline EuRh2As2

An antiferromagnetic transition is observed in single-crystal EuRh2As2 at a high temperature T-N=47 K compared to the ferromagnetic Weiss temperature theta=12 K. We show that the large ratio T-N/vertical bar theta vertical bar approximate to 4 is, perhaps surprisingly, consistent with mean-field theory. A first-order field-induced magnetic transition is observed at T < T-N with an unusual temperature dependence of the transition field. A dramatic magnetic field-induced reduction in the electronic specific heat coefficient at 1.8-5.0 K by 38% at 9 T is observed. In addition, a strong positive magnetoresistance and a large change in the Hall coefficient occur below 25 K. Band structure calculations indicate that the Fermi energy lies on a steep edge of a narrow peak in the density of states.