Electrical control of the ferromagnetic phase transition in cobalt at room temperature

Abstract

Electrical control of magnetic properties is crucial for device applicationsin the field of spintronics^{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20}. Although the magnetic coercivity or anisotropy has been successfully controlled electrically in metals ^9,15,17 as well as in semiconductors^6,10,11,13, the electrical control of Curie temperature has been realized only in semiconductors at low temperature^4,5,8. Here, we demonstrate the room-temperature electrical control of the ferromagnetic phase transition in cobalt, one of the most representative transition-metal ferromagnets. Solid-state field effect devices consisting of a ultrathin cobalt film^21,22 covered by a dielectric layer and a gate electrode were fabricated. We prove that the Curie temperature of cobalt can be changed by up to 12 K by applying a gate electric field of about ±2 MV cm⁻¹. The two-dimensionality of the cobalt film may be relevant to our observations. The demonstrated electric field effect in the ferromagnetic metal at room temperature is a significant step towards realizing future low-power magnetic applications.