Magnetic Phase Diagram in NdCu4Ag Single Crystal

The magnetic properties of cubic intermetallic compound NdCu4Ag single crystals were studied in detail through magnetization, susceptibility, specific heat and electrical resistivity measurements. An observed anomaly in C(T) with a sharp peak 26 J/(mol K) at 4.2 K, together with an antiferromagnetic behavior of chi(T), indicated that an antiferromagnetic phase transition occurred at this temperature. Anisotropic properties in M(H), chi(T), and C(T) at external fields were investigated in directions of [001], [110], and [111], respectively. Two metamagnetic transitions were observed below the Neel temperature T-N when a magnetic field was applied in three directions. In all the three directions, T-N decreased with an increase in magnetic field and new anomalies induced by a high H-ext were observed in both chi(T) and C(T), implying that two new magnetic phases coexisted with the antiferromagnetic phase. From the specific heat measurements, it is speculated that the crystalline electric field ground state of Nd3+ (J = 9/2) ions is the Gamma(8) quartet for NdCu4Ag. From these anomalies, the magnetic phase diagram of NdCu4Ag was determined.