Instability of Co Spin Moment in ErCo sub( 2) Probed by Magnetic Compton Scattering under High Pressure

Magnetic Compton scattering at high pressure is presented for the first time. To study the pressure-induced magnetic transition in Laves-phase ErCo 2 , Er 4 f and Co 3 d spin magnetic moments, together with the conduction electron component, were separately and quantitatively estimated at pressures up to 1.84 GPa. The Co 3 d spin moments show a remarkable reduction with increasing pressure, which is in contrast to the weak pressure variation of the Er 4 f spin moment. The relationship between the magnetic transition and instability of the Co 3 d moment at high pressure is discussed from the viewpoint of lattice contraction and the molecular field of Er 4 f moments.