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Temperature dependence of resistance in epitaxial Fe/MgO/Fe magnetic tunnel junctions. Q. L. Ma, S. G. Wang, and X. F. Han. Group M02, State Key Laboratory of Magnetism Institute of Physics, CAS. Abstract.

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  1. Temperature dependence of resistance in epitaxial Fe/MgO/Fe magnetic tunnel junctions Q. L. Ma, S. G. Wang, and X. F. Han Group M02, State Key Laboratory of Magnetism Institute of Physics, CAS Abstract The temperature dependence of resistance in parallel (P) and antiparallel (AP) configurations (RP,AP) has been investigated in epitaxial Fe/MgO/Fe junctions with varying MgO barrier thicknesses tMgO. RAP exhibits a substantial decrease with increasing temperature for samples with tMgO ranging from 3.0 to 1.5 nm. In contrast, RP is approximately temperature independent when tMgO =3.0 nm and increases with temperature when tMgO=2.1 and 1.5 nm. A mode based on misalignment of magnetic moment in the electrodes due to thermal excitations was used to describe this temperature dependent of TMR ratio. (1) (2) (a) (b) (3) (1) Sketch of MTJ structure and measurement set- up (a), HRTEM image (b) of Fe/MgO/Fe trilayers. (2) Normalized TMR ratio at 4.2 K in junctions. (3) Temperature dependence of RA in the P and AP states for tMgO=1.5 nm, where the lines are fits based on the model (Formula as follow). (4) Temperature dependent of the TMR ratio for junctions with tMgO =3.0, 2.1 and 1.5 nm, where open points represent experimental data and solid lines represent fits. http://www.m02group.com (4) is a material-dependent constant ( ) denotes saturation magnetizations of two magnetic layers at T=0 K includes the proportionality factor relating spin polarization, magnetization and the local interface effect on the spin-polarized electron tunneling Conclusion RP is reported to increase with temperature in epitaxial magnetic junctions with thin MgO barriers 2.1 and 1.5 nm. The temperature dependence of RP,AP originates from the misalignment of magnetic moments in the electrodes due to thermal excitations. Conversely, we find that in these epitaxial Fe/MgO/Fe junctions the spin independent term and spin flip scattering are not significant factors in determining the temperature dependence of RP,AP. Q. L. Ma et al., Appl. Phys. Lett. 95, 052506 (2009), S. G. Wang et al., Phys. Rev. B. 78, 180411(R) (2008) This project was supported by MOST, NSFC, and CAS, and in collaboration with Dr. R. Ward at Oxford University

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