Thin-film magnetic sensors using topological materials

Abstract

Giant magnetic responses and magneto-thermoelectric phenomena emerging in topological materials hold promise for applications in the next generation of electronics. Inspired by the remarkable properties in crystals of a topological ferromagnet Fe₃Sn₂, we have been involved with developing Hall devices using amorphous-like thin films of a ferromagnetic alloy of Fe_0.6Sn_0.4 as a more versatile material form. The amorphous-based device is composed of inexpensive and environmentally benign elements, potentially offering new applications that take advantage of the high temperature stability of the device itself and the mechanical flexibility of the metallic film. As the magnetoresistance effect specific to magnetic materials can be measured simultaneously with the anomalous Hall effect, this device can be applied to the detection of three-dimensional (3D) magnetic field vector with a single planar-type structure. In this paper, we overview the operating principles of various thin-film magnetic sensors and introduce the fabrication method and basic properties of Fe–Sn amorphous-like thin films as well as the principles and characteristics of two devices: a cross-shaped Hall device and a planar-type 3D magnetic field sensor.