2017/11/15 by Filip Schleicher, Schleicher, F., Beata Taudul +29
Engineering · Materials Science · #Electronic and Structural Properties of Oxides #FOS: Physical sciences #Magnetic and transport properties of perovskites and related materials #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Semiconductor materials and devices
paper · pdf · doi:10.48550/arxiv.1711.05643
openalex publication_date 2017/11/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The quantum mechanical tunnelling process conserves the quantum properties of the particle considered. As applied to solid-state tunnelling (SST), this physical law was verified, within the field of spintronics, regarding the electron spin in early experiments across Ge tunnel barriers, and in the 90s across Al2O3 barriers. The conservation of the quantum parameter of orbital occupancy, as grouped into electronic symmetries, was observed in the '00s across MgO barriers, followed by SrTiO3 (STO). Barrier defects, such as oxygen vacancies, partly conserve this electronic symmetry. In the solid-state, an additional subtlety is the sign of the charge carrier: are holes or electrons involved in transport? We demonstrate that SST across MgO magnetic tunnel junctions (MTJs) with a large resistance-area (RA) product involves holes by examining how shifting the MTJ's Fermi level alters the ensuing barrier heights defined by the barrier's oxygen vacancies. In the process, we consolidate the description of tunnel barrier heights induced by specific oxygen-vacancy induced localized states. Our work opens prospects to understand the concurrent observation of high TMR and spin transfer torque across MgO-based nanopillars.