Study of ferromagnetic transition in Pd nanometer-scale constrictions using a mechanically controllable break junction technique

We measured the magnetoresistance (MR) of Pd nanometer-scale constrictions while changing the constriction size by stretching the Pd wire using a mechanically controllable break junction technique. In large constrictions, the resistance is constant for | H | 400 Oe, reflecting bulk Pd paramagnetic properties. As size decreases to ∼10 nm, the MR effect with hysteresis is observed with a sweeping field, indicating the ferromagnetic transition in Pd constrictions. We proposed this technique to detect ferromagnetic transitions caused by downsizing in paramagnetic metals and to study magnetic properties after the transitions.