Strontium ferromolybdate-based magnetic tunnel junctions

Abstract

Thin-film strontium ferromolybdate is a promising material for applications in room-temperature magnetic tunnel junction devices. These are spin-based, low-power-consuming alternatives to CMOS in non-volatile memories, comparators, analog-to-digital converters, and also in magnetic sensors. In this work, we consider the main tasks to be solved when creating such devices based on strontium ferromolybdate: (i) selection of an appropriate tunnel barrier material, (ii) role of the interface roughness and (iii) its quantification, (iv) influence of the interface dead layer, (v) appropriate models of the tunnel magnetoresistance, and (vi) promotion of the low-field magnetoresistance in (111)-oriented thin films. We demonstrate that (i) barrier materials with a lower effective electronegativity than strontium ferromolybdate are beneficial, (ii) diminution of the magnetic offset field (the latter caused by magnetic coupling) requires a wavy surface rather than solely a surface with small roughness, (iii) the interface dead-layer thickness is on the order of 10 nm, (iv) the tunnel magneto-resistance deteriorates due to spin-independent tunnelling and magnetically disordered interface layers, and (v) antiphase boundaries along the growth direction promote the negative low-field magneto-resistance by reducing charge carrier scattering in the absence of the field.