Anomalous Magnetization of RbFeCl3around 31T in Pulsed High Magnetic Fields

Abstract
Magnetizations of the triangular antiferromagnets RbFeCl 3 and RbFeBr 3 are measured in pulsed high magnetic fields up to 40T at liquid 4 He temperatures. In the case of RbFeCl 3 , the magnetization is found to increase almost linearly from the zero field, and to be flattened at some critical field of 14T. Further application of magnetic fields induces an anomalous double-step magnetization around 31T. The phenomenon is similar to the one which was found in CsFeCl 3 at some higher magnetic field, but noteworthy is the existence of a fine structure in the anomalous magnetization of RbFeCl 3 . The anomaly has thus far not been observed for RbFeBr 3 in the measured magnetic fields up to 85T.