Magnetic Damping Study by Broadband Ferromagnetic Resonance

Overview

Objectives (a) Broadband (1 GHz to 15 GHz) microwaves are applied to magnetic samples and magnetic resonance occurs when the resonance condition is met; (b) High accuracy is achieved when the magnetic field is modulated and the corresponding response is detected; (c) Yttrium iron garnet (YIG) thin film sample is chosen because of its narrow resonance linewidth; (d) From the resonance peak width at different frequencies, the Gilbert damping parameter is determined; (e) A 5 nanometer thick (BiSb)2Te3 (BST) overlayer is deposited on YIG thin film and the Gilbert damping parameter is determined again and compared. Methods (a) Broadband (1 GHz to 15 GHz) microwaves are applied to magnetic samples and magnetic resonance occurs when the resonance condition is met; (b) High accuracy is achieved when the magnetic field is modulated and the corresponding response is detected; (c) Yttrium iron garnet (YIG) thin film sample is chosen because of its narrow resonance linewidth; (d) From the resonance peak width at different frequencies, the Gilbert damping parameter is determined; (e) A 5 nanometer thick (BiSb)2Te3 (BST) overlayer is deposited on YIG thin film and the Gilbert damping parameter is determined again and compared. Results At each microwave frequency, the magnetic resonance absorption can be fitted very well by a Lorentzian function. Extracted full-width at half maximum at different microwave frequencies is used to calculate the Gilbert damping parameter of the magnetic material. The 5 nanometer thick BST overlayer is found to have a significant effect on magnetic damping of YIG thin film. The Gilbert damping parameter is found to increase by a factor of four with the addition of the BST overlayer. Conclusions The experimental results indicate that strong atomic scale interaction between BST and YIG at the interface plays an important role in enhancing magnetic damping. The results also raise questions for future studies including whether the atomic arrangement in BST is important, how the relative concentration of Bi and Sb atoms in BST affect the results.

Competition history

• CSEF 2019 Physics & Astronomy · Entry S1716

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