Insertion Trade-off Effects on the Spin-Transfer Torque Memory Explored by In Situ X-ray

Abstract

Magnetoresistive random-access memory (MRAM) relies on magnetic tunnel junctions (MTJs) comprising heterostructures of CoFeB/MgO/CoFeB. Nonetheless, the dielectric breakdown of MgO limits the lifespan of MRAM devices. In the current study, we terminated MgO with a Mg surface facing the CoFeB free layer to reduce the mismatch in band alignment across the barrier. The Mg-modified interface was shown to enhance the breakdown voltage while reducing the switching current and asymmetric switching behavior, with a moderate sacrifice of perpendicular magnetic anisotropy, tunneling magnetoresistance, and resistance−area product. This performance trade-off was observed in all MTJs, regardless of cell size (180, 130, and 80 nm; each size has been tested with at least 20 cells). Visualization of the proposed junction via in situ X-ray absorption spectroscopy proved effective in elucidating the reconstruction of the interface within the context of energy barrier height, asymmetric switching behavior, and the voltage-driven movement of oxygen ions. A spindependent band diagram was constructed to correlate the tunneling/switching properties of the MTJ with such a trade-off scenario. The atomistic simulation of the magnetic properties revealed that Mg termination lowered the switching energy barrier with an effective domain wall motion within the CoFeB free layer.

Interface imperfection effects on spin transfer torque switching: an atomistic approach

“…Note however that increasing roughness at the interface can also affect interface anisotropy and enable faster switching. This imposes a tradeoff between the performance parameters of p-MTJs [13]. In the atomistic simulation of roughness, magnetic properties are assigned separately for bulk CoFeB and the CoFeB interface.…”

“…boron diffusion) [11]. Numerous methods have been suggested to study performance issues related to interface effects [12,13]. Note however that MRAM performance also depends on the physical properties and magnetization dynamics of the constituent magnetic materials [14].…”

Biological sensing using anomalous hall effect devices

“…In addition, PMA samples are prone to superparamagnetic states, which can be effectively used for sensors [16]. Additionally, CoFeB(X)/MgO structure is the mainstream material for the MRAM [17,18] which makes it industry compatible. In the current study, we developed a novel magnetic biosensor with CoFeB/MgO heterostructure having PMA.…”