MAGNETIC AND ELASTIC PROPERTIES IN THE PARAMAGNETIC STATE OF NDIN3 ANTIFERROMAGNET

The cubic AuCu3 type system NdIn3 exhibits complex magnetic structures at low temperature. Immediately below the Neel temperature, T(N) = 6 K, the spins assume a sine wave modulated arrangement; for 5.5 K > T > 4.7 K, the modulation tends towards a square wave. Finally, below 4.7 K, a simple commensurate structure is stabilized. We first confirm here the complex magnetic phase diagram by means of resistivity measurements. In order to quantitatively understand the low temperature properties, the crystalline electric field is determined by inelastic neutron spectroscopy. An extensive study of the magnetic, magnetoelastic and quadrupolar properties in the paramagnetic phase by magnetization, ultrasonic velocity and parastriction measurements is then presented. The values of one-ion magnetoelastic coefficients agree with previous determinations in isomorphous systems. Quadrupolar pair interactions are found to be positive for the tetragonal symmetry lowering mode, in agreement with the symmetry of collinear magnetic structures. However the only quadrupolar model fails to coherently describe the whole set of paramagnetic properties, in particular the third order magnetic susceptibility. The existence of two-ion magnetoelasticity is then discussed in relation to the ultrasonic velocity and parastriction results. The description of the magnetic phase diagrams will be reported elsewhere.