SPECIFIC-HEAT OF NDCU2 AT VERY-LOW TEMPERATURES

NdCu2 undergoes successive magnetic transitions at 6.5 and 4.1 K, resp ectively. We extend the previous specific-heat measurements to below 1 K and to magnetic fields up to 6 T. The specific heat C below 3 K dec reases exponentially, indicating a gap of 10.3 K.k(B) in the magnetic excitation spectrum and hence a rather strong magnetic anisotropy. Bel ow 0.8 K C increases towards low T because of the hyperfine contributi on of Nd. In a magnetic field of 6 T applied parallel to the b directi on of orthorhombic NdCu2, the gap increases to 12.8 K.k(B). Determinat ion of the magnetic transitions by measurements of C in a magnetic fie ld and by the magnetocaloric effect complements the (B, T) phase diagr am of NdCu2.