Anomalous magnetoresistance at low temperatures (T <= 10 K) in a single crystal of GdB4

Abstract

We successfully synthesized pure single crystals of GdB4, which reveals RRR=550, defined as RRR p(300 K) / rho(2 K). The temperature derivative of resistivity dp(T)/dT shows a transitionlike change of electronic property at Ta approximate to 10 K, in addition to the known antiferromagnetic transition at T-N=42 K. We also found that the rho(T) shows an anomalous increase under the applied magnetic fields H below T, which leads to a positive magnetoresistance ratio MR=-[p(H,T) -rho(0,T)]/rho(0,T)=58 800% at T=2 K and H=7 T. Furthermore, the electronic feature near T,, manifests itself by a broad bump near T 10 K in a specific heat measurement, which indicates that the transition at T, is a bulk property. We found that the positive and large magnetoresistance can be described by an empirical function, based on Kohler&apos;s rule for the electron dynamics of a pure simple metal. (c) 2005 American Institute of Physics.