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 magnetic sensors. In this work, we consider the main tasks to be solved when creating such devices based on strontium ferromolybdate: (i) selecting an appropriate tunnel barrier material, (ii) determining the role of the interface roughness and its quantification, (iii) determining the influence of the interface dead layer, (iv) establishing appropriate models of the tunnel magnetoresistance, and (v) promoting 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 of the order of 10 nm, (iv) the tunnel magnetoresistance deteriorates due to spin-independent tunneling and magnetically disordered interface layers, and (v) antiphase boundaries along the growth direction promote the negative low-field magnetoresistance by reducing charge carrier scattering in the absence of the field.

The Influence of Annealing and Film Thickness on the Specific Properties of Co40Fe40Y20 Films

“…More liquid is also absorbed when the surface free energy is high. The contact angle and Young’s equation are used to derive the surface energy [ 29 , 30 , 31 ]. Low surface energy is correlated with weak adhesion [ 49 ].…”

“…Additionally, contact angle measurements are a suitable and simple way to determine the surface energy using water and glycerol when taking into account the application of the film, which is a dominant factor in molecular interaction at the surface [ 28 ]. In most cases, researchers have emphasized the properties in light of the magnetic hysteresis curve, Ms, and Hc [ 29 , 30 , 31 ]. However, it will be interesting to learn how the variation of surface energy and optical transmittance can be correlated with the magnetic properties of the deposited films.…”

Tunnel Spin-Polarization of Ferromagnetic Metals and Ferrimagnetic Oxides and Its Effect on Tunnel Magnetoresistance

“…Due to this reason, the experimental data of SFMO and Fe 3 O 4 are lower than the calculated ones. In the case of SFMO, the value of the coefficient β SI (298 K) amounts to about 0.1 [35]. On the other hand, the discovery of the coherent tunneling effect at Fe(100)/MgO(100) boundaries enables theoretically MR values of up to 1000% [9][10][11][12].…”

“…Supposing an ASD of about 10% and P 0 = 0.9 [34], we arrive at TMR values for SFMO of 214% and 11% at 4 K and room temperature, respectively. Taking spin-independent tunneling into account, the attainable TMR yields [35]…”