Post-oxidized Mg-Al-O(001) coherent tunneling barrier in a wide range of resistance-area products

作者：Sukegawa Hiroaki^*; Inomata Koichiro; Mitani Seiji

来源：Applied Physics Letters, 2014, 105(9): 092403.

DOI：10.1063/1.4895104

We fabricated epitaxial Mg-Al-O(001) tunnel barriers using direct/indirect plasma oxidation and natural oxidation of an MgAl layer for use in Fe/Mg-Al-O/Fe magnetic tunnel junctions. All the oxidation processes formed epitaxial Mg-Al-O barriers, and a wide resistance area (RA) product range (10(1) - 10(6) Omega.mu m(2)) and large tunnel magnetoresistance (TMR) ratios (185%-212%) at room temperature were achieved by optimizing the MgAl thickness (t(MgAl)). Near optimum oxidation conditions and tMgAl, small bias voltage dependence of the TMR ratio, and distinct local minima in the dI/dV spectra for the parallel magnetic configuration were observed, indicating that coherent tunneling transport was significant. This study showed that Mg-Al-O coherent tunnel barriers have excellent formability in a wide RA product range.

• 出版日期2014-9-1