Magnetic phase transitions in Nd7Rh3 single crystal

Magnetic phase transitions in rare earth intermetallic compound Nd7Rh3 have been investigated using a single crystal. Measurement results of magnetization, magnetic susceptibility, specific heat, and electrical resistivity reveal that Nd7Rh3 has two magnetic phase transitions at TN=34 K, Tt2=9.1 K and a change of the magnetic feature at Tt1=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 Tt2, 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 MR is stabilized. The MR 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 Tt2. In the antiferromagentic state above Tt2, 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 Gd5Ge4 can be considered.