COMPETING ANISOTROPIES IN THE FERROMAGNETIC KONDO-LATTICE COMPOUND YBNISN - OBSERVATION OF A COMPLEX MAGNETIC GROUND-STATE UNDER HIGH-PRESSURE

The Yb-170 high pressure Mossbauer-effect technique has been used to i nvestigate on a microscopic level the ground state properties of the f erromagnetic (FM) Kondo-Iattice compound YhNiSn. Unlike general expect ations, we find for 0 less than or equal to p less than or equal to 3 GPa a stable moment behavior while T-C is enhanced to its maximum valu e. For p > 3 GPa we observe a gradual change of the FM state to a comp lex magnetic ground state, This is suggested to be due to a volume dep endent competition between the anisotropy of the magnetic exchange int eraction and the crystal electric field anisotropy.