METAL-INSULATOR-TRANSITION IN YTTERBIUM UNDER PRESSURE - AN EPR STUDY

We study the pressure-induced metal-insulator (MI) transition in ytter bium using EPR measurements with Eu as the probe for magnetic resonanc e. For a given pressure the linewidth Delta H increases Linearly with temperature indicating a Korringa type of relaxation of the Eu impurit ies by the conduction electrons of the host. With increasing pressure d Delta H/dT decreases becoming very small at a critical pressure P-c approximate to 12.5 kbars. Close to P-c, d Delta H/dT decreases linear ly with (P - P-c) in agreement with the scaling theory for density-dri ven metal-insulator transitions. To the best of our knowledge, this is the first time such transitions are studied by magnetic resonance.