Fabrication of fully epitaxial magnetic tunnel junctions using L21-ordered Co2FeAl0.5Si0.5 electrodes and their tunneling magnetoresistance characteristics

Wenhong Wang; Sukegawa, Hiroaki; Rong Shan; Inomata, Koichiro
September 2008
Applied Physics Letters;9/22/2008, Vol. 93 Issue 12, p122506
Academic Journal
Magnetic tunnel junctions (MTJs) using L21-ordered full-Heusler Co2FeAl0.5Si0.5 (CFAS) electrodes and an MgO tunnel barrier were prepared on MgO-buffered MgO (001) substrates by sputtering method. In situ and ex situ structural characterization confirms that the stacking structure of CFAS/MgO/CFAS is fully epitaxial, with smooth interfaces throughout. The microfabricated MTJs exhibited relatively high tunnel magnetoresistance ratios of 150% at room temperature and 312% at 7 K. We observed a symmetrical crossover point from the bias voltage dependence of differential conductance between parallel and antiparallel magnetization configurations, and also a flat behavior in the parallel conductance, which can be explained by considering the characteristic half-metallic band structure of L21-ordered CFAS near the Fermi level.


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