MAGNETIC FRUSTRATION IN THE ANTIFERROMAGNETIC KONDO-LATTICE YBPTAL, ANOMALOUS MAGNETIC-BEHAVIOR AT HIGH-PRESSURES

We have investigated the magnetic and electronic properties of the ant iferromagnetic Kondo lattice YbPtAl using the Yb-170 Mossbauer effect at ambient pressure (1.8 < T < 10 K), electrical resistance (1.8 < T < 300 K) and X-ray diffraction (T = 300 K) techniques at high pressures up to 26 GPa. We find a complex magnetic state in YbPtAl at ambient p ressure and an unusual volume-induced change of T-N. It is suggested, that the anomalous volume dependence of T-N is due to the interplay be tween frustrated anisotropic exchange interactions and magnetocrystall ine anisotropy. The magnetic frustration originates from the topology of the crystal lattice. (C) 1998 Elsevier Science B.V. All rights rese rved.