Electrically driven magnetism on a Pd thin film

TL;DR

This paper demonstrates through first-principles calculations that applying an electric field to a Pd thin film can induce and control surface ferromagnetism by altering the electronic density of states, enabling electric-field-driven magnetic transitions.

Contribution

It introduces a method to electrically induce and modulate ferromagnetism on Pd surfaces, revealing a controllable magnetic transition driven by electric fields.

Findings

Electric field induces ferromagnetism on Pd surface.

Surface magnetization varies with electric field near transition.

Magnetic moment follows a square-root dependence on electric field.

Abstract

Using first-principles density functional calculations we demonstrate that ferromagnetism can be induced and modulated on an otherwise paramagnetic Pd metal thin-film surface through application of an external electric field. As free charges are either accumulated or depleted at the Pd surface to screen the applied electric field there is a corresponding change in the surface density of states. This change can be made sufficient for the Fermi-level density of states to satisfy the Stoner criterion, driving a transition locally at the surface from a paramagnetic state to an itinerant ferromagnetic state above a critical applied electric field, Ec. Furthermore, due to the second-order nature of this transition, the surface magnetization of the ferromagnetic state just above the transition exhibits a substantial dependence on electric field, as the result of an enhanced magnetoelectric susceptibility. Using a linearized Stoner model we explain the occurrence of the itinerant ferromagnetism and demonstrate that the magnetic moment on the Pd surface follows a square-root variation with electric field consistent with our first-principles calculations.