Room-temperature operation of a vertical spin field-effect transistor using an Fe / GaO_x / MgO / Fe system

摘要

A spin metal-oxide semiconductor field-effect transistor (spin MOSFET), in which the source and drain electrodes are ferromagnetic materials, has been intensively studied for future electronics applications [1,2]. Recently, a vertical spin field-effect transistor (FET), in which the current flows perpendicular to the plane and is controlled by the gate voltage applied from the side surface of the channel, is attracting considerable attention because it exhibits larger magnetoresistance (MR) ratios (60% [3], 5% [4], and 7% [5]) than the lateral spin MOSFETs (0.1% [6], 0.005% [7], and 0.027% [8]). Previously, we demonstrated large MR in vertical spin FETs using ferromagnetic-semiconductor GaMnAs-based heterostructures [3-5]. However, owing to the low Curie temperature of GaMnAs (く 200 K), room-temperature operation of vertical spin FETs has not been demonstrated yet.