Electron transport in ferromagnet/InAs hybrid transistors

We have prepared metal-oxide field-effect transistors with ferromagnetic source- and drain contacts by electron-beam lithography on p-type InAs single crystals. This narrow gap semiconductor exhibits strong spin-orbit coupling, which can be tuned by a gate voltage. The permalloy electrodes are used to drive a spin-polarized current in the ballistic limit through the quasi two-dimensional electron system of the inversion layer on the semiconductor. The field effect is examined as a function of the gate voltage in external magnetic fields applied in-plane and thus parallel to the current direction. In this configuration the resistance exhibits strong evidence for spin-polarized transport via an oscillatory gate-voltage dependence of the resistance jumps at the magnetization reversals of the ferromagnetic electrodes.