Influence of MgO tunnel barrier thickness on spin-transfer ferromagnetic resonance and torque in magnetic tunnel junctions

Spin-transfer ferromagnetic resonance (ST-FMR) in symmetric magnetic tunnel junctions (MTJs) with a varied thickness of the MgO tunnel barrier (0.75 nm < t sub(MgO) < 1.05 nm> is studied using the spin-torque diode effect. The application of an rf current into nanosized MTJs generates a dc...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2013-03, Vol.87 (9), Article 094419
Main Authors: Skowroński, Witold, Czapkiewicz, Maciej, Frankowski, Marek, Wrona, Jerzy, Stobiecki, Tomasz, Reiss, Günter, Chalapat, Khattiya, Paraoanu, Gheorghe S., van Dijken, Sebastiaan
Format: Article
Language:English
Subjects:
Barriers
Condensed matter
Direct current
Electric potential
Magnesium oxide
Torque
Tunnels (transportation)
Voltage
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Summary:Spin-transfer ferromagnetic resonance (ST-FMR) in symmetric magnetic tunnel junctions (MTJs) with a varied thickness of the MgO tunnel barrier (0.75 nm < t sub(MgO) < 1.05 nm> is studied using the spin-torque diode effect. The application of an rf current into nanosized MTJs generates a dc mixing voltage across the device when the frequency is in resonance with the resistance oscillations arising from the spin-transfer torque. Magnetization precession in the free and reference layers of the MTJs is analyzed by comparing ST-FMR signals with macrospin and micromagnetic simulations. From ST-FMR spectra at different dc bias voltage, the in-plane and perpendicular torkances are derived. The experiments and free electron model calculations show that the absolute torque values are independent of tunnel barrier thickness. The influence of coupling between the free and reference layer of the MTJs on the ST-FMR signals and the derived torkances are discussed.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.87.094419