Magnetic phase transitions in Nd 7Rh 3 single crystal

Abstract

Magnetic phase transitions in rare earth intermetallic compound Nd 7Rh 3 have been investigated using a single crystal. Measurement results of magnetization, magnetic susceptibility, specific heat, and electrical resistivity reveal that Nd 7Rh 3 has two magnetic phase transitions at T N=34 K, T t2=9.1 K and a change of the magnetic feature at T t1=6.8 K in the absence of an external magnetic field. Antiferromagnetic orderings exist in all the three magnetic states; a large magnetic anisotropy between the c-axis and the c-plane is observed. In the magnetic phase below T t2, an irreversible field-induced magnetic phase transition takes place in the c-plane; after removing external magnetic field, a coexistence state of ferro- and antiferromagnetic ordering or a ferrimagnetic state having a remanent magnetization M R is stabilized. The M R decays to a certain value for several hours after the first process; a magnetic field cooling effect was also observed in the c-plane below T t2. In the antiferromagentic state above T t2, the irreversibility disappears and an ordinary antiferromagnetic state takes place. As the origin of this phenomenon, a kind of martensitic structural transition that is observed in Gd 5Ge 4 can be considered.