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Spin pumping in magnetic trilayer structures with an MgO barrier

DOI: 10.1038/srep35582 DOI Help

Authors: Alexander Baker (Diamond Light Source, University of Oxford) , Adriana Figueroa-garcia (Diamond Light Source) , D. Pingstone (University of York) , V. K. Lazarov (University of York) , G. Van Der Laan (Diamond Light Source) , Thorsten Hesjedal (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Scientific Reports , VOL 6

State: Published (Approved)
Published: October 2016
Diamond Proposal Number(s): 11501

Open Access Open Access

Abstract: We present a study of the interaction mechanisms in magnetic trilayer structures with an MgO barrier grown by molecular beam epitaxy. The interlayer exchange coupling, Aex, is determined using SQUID magnetometry and ferromagnetic resonance (FMR), displaying an unexpected oscillatory behaviour as the thickness, tMgO, is increased from 1 to 4 nm. Transmission electron microscopy confirms the continuity and quality of the tunnelling barrier, eliminating the prospect of exchange arising from direct contact between the two ferromagnetic layers. The Gilbert damping is found to be almost independent of the MgO thickness, suggesting the suppression of spin pumping. The element-specific technique of x-ray detected FMR reveals a small dynamic exchange interaction, acting in concert with the static interaction to induce coupled precession across the multilayer stack. These results highlight the potential of spin pumping and spin transfer torque for device applications in magnetic tunnel junctions relying on commonly used MgO barriers.

Journal Keywords: Magnetism, Spintronics, XFMR, XMCD

Subject Areas: Physics, Materials, Technique Development

Diamond Offline Facilities: SQUID-VSM Magnetometer (Quantum Design), Magnetic Spectroscopy Lab
Instruments: I10-Beamline for Advanced Dichroism

Other Facilities: ALS-Berkeley