Electrically Controlled Magnetoresistance in Ion-Gated Platinum Thin Films

Electric-field-induced correlated states of matter are an important topic in solid-state research. The recent revival of the ionic gating technique allows modulation of the carrier density even on metal surfaces. Here, we show that the anomalous magnetoresistance induced in ion-gated paramagnetic platinum thin films can be analyzed in the framework of an induced ferromagnetic phase on a platinum surface. The temperature dependence of the anomalous Hall component extracted from the observed superlinear Hall resistance was described well by using the Bloch equation for ferromagnetism. Moreover, a negative longitudinal magnetoresistance was observed at small angles between the film’s plane and magnetic field, consistent with the behavior of ferromagnetic metal alloys.