Spin-dependent tunneling in HfO2 tunnel junctions

Abstract

We identified reactively sputtered HfO2 as a particularly good material for making thin insulating barriers for spin-dependent tunnel junctions. This material allows one to form pinhole-free tunnel barriers with good transmission of the spin polarization of the tunneling electrons. Magnetic tunnel junctions consisting of a thin layer of HfO2 sandwiched between transition metal electrodes (Co and Fe, for instance) exhibit changes of tunnel resistance up to 30% at low temperature as a function of applied field. This effect can be used in a variety of magnetic field sensing applications or in magnetic random access memory.