Spin-dependent tunnel junctions with ZrO[sub x] barriers

Wang, Jianguo; Freitas, P. P.; Snoeck, E.; Wei, P.; Soares, J. C.
December 2001
Applied Physics Letters;12/24/2001, Vol. 79 Issue 26, p4387
Academic Journal
Spin-dependent tunnel junctions with crystalline ZrO[sub x] barriers were fabricated, with tunnel magnetoresistance (TMR) reaching 20% and a resistance×area product of 24 k Ω μm[sup 2], after annealing at 260 °C. Effective barrier height and thickness are 1.6 eV and 10.6 Å, respectively. The ZrO[sub x] barriers were fabricated by rf plasma oxidation of a 5 Å thick Zr layer. High-resolution transmission electron microscopy and Rutherford backscattering spectrometry were used to characterize the as-deposited barrier. Both ZrO and ZrO[sub 2] phases are present, together with (CoFe)O[sub x]. Upon annealing, the interfacial oxygen moves into the barrier, resulting in an increase of TMR from 2% to 19.2%, an increase of barrier height from 0.3 to 1.6 eV, and a reduction of barrier thickness from 18.5 to 10.5 Å. © 2001 American Institute of Physics.


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