Magnetic Phase Diagram in the Canting Antiferromagnet NdCu6

Abstract

For NdCu 6 with successive four antiferromagnetic transitions below the Neel temperature of T N =6.10 K, high resolution measurements of the specific heat and ac magnetic susceptibility were performed synchronously in magnetic fields up to 4 T applied along the three crystallographic axes of the orthrohmbic structure. Phase diagrams of NdCu 6 were derived from the results of field dependences of the four magnetic phases corresponding to the four specific heat peaks. The three of the phases disappear at 0.5 T applied along the c -axis, but for the a -axis these almost remain. We have revealed an unusual feature of the phase diagram in which the three phase lines connect with the spin flop-line for magnetic fields applied along the b -axis. We also discussed the expected magnetic structure of NdCu 6 with respect to the results of the magnetic susceptibility measurements.