High-TMR iron-free double-barrier MTJs with MoTe<sub>2</sub> spacing for label-free magnetic biosensors.

Abstract

Double-barrier magnetic tunnel junctions (DB-MTJs) present a promising platform for biosensing applications due to their improved sensitivity and capability for label-free, non-invasive detection. This work models a high-performance iron-free DB-MTJ configuration: Co₂MnSi-MgO-MoTe₂-MgO-Co₂MnSi. By Utilizing density functional theory (DFT) and the nonequilibrium Green's function (NEGF) technique, we computed the tunnelling magnetoresistance (TMR) ratio, transmission spectra, density of states (DOS), and bandgaps for the Co₂MnSi-MgO-MoTe₂-MgO-Co₂MnSi system. The DB-MTJ features iron-free Co₂MnSi Heusler alloy electrodes and a MoTe₂ transition metal dichalcogenide (TMDC) spacer, achieving a tunneling magnetoresistance (TMR) ratio of 1226%, alongside other configurations with TMR ratios ranging from 22% to 667%. The high TMR, driven by the tunable electronic properties of MoTe₂ and the half-metallic nature of Co₂MnSi, enables exceptional sensitivity to interfacial modifications, making it ideal for detecting biomarkers. The application of iron-free materials increases the electrodes' stability and spin polarization and improves the sensitivity of the DB-MTJs upon interface variations. This research points out the high-potential applications of Heusler-based and iron-free DB-MTJ's as sensitive and label-free biosensors.