Spin transfer torque in magnetic tunnel junctions

Chen Wang, Cornell University

The transfer of spin angular momentum from a spin-polarized current to a ferromagnet can generate sufficient torque to reorient the magnet’s moment. This spin transfer torque is particular interesting in the case of MgO-based magnetic tunnel junctions because of its widely pursued application in magnetic random access memory (MRAM) devices and its role as a probe of spin dependent tunneling physics. Here I will describe two complementary experiments that study ferromagnetic resonance driven by the spin transfer torque and allowed us to achieve the first quantitative measurement of spin transfer torque across the full bias range at various angles in magnetic tunnel junction. In addition, I will also present our recent study of spin transfer torque in ferromagnetic nanoparticles (2-3 nm in size) from spin-polarized tunneling current.

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