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Uncooled sub-GHz spin bolometer driven by auto-oscillation

2021; Nature Portfolio; Volume: 12; Issue: 1 Linguagem: Inglês

10.1038/s41467-020-20631-0

2041-1723

Minori Goto, Yuma Yamada, Atsushi Shimura, Tsuyoshi Suzuki, Naomichi Degawa, Takekazu Yamane, Susumu Aoki, Junichiro Urabe, Shinji Hara, Hikaru Nomura, Yoshishige Suzuki,

Superconducting and THz Device Technology

Abstract Bolometers are rectification devices that convert electromagnetic waves into direct current voltage through a temperature change. A superconducting bolometer has a responsivity of approximately 10 6 –10 7 V/W under cryogenic temperatures at infrared wavelengths; however, no devices have realized such a high responsivity in the sub-GHz frequency region. We describe a spin bolometer with a responsivity of (4.40 ± 0.04) × 10 6 V/W in the sub-GHz region at room temperature using heat generated in magnetic tunnel junctions through auto-oscillation. We attribute the unexpectedly high responsivity to a heat-induced spin-torque. This spin-torque modulates and synchronizes the magnetization precession due to the spin-torque auto-oscillation and produces a large voltage output. In our device, heat-induced spin-torque was obtained because of a large heat-controlled magnetic anisotropy change: −2.7 µJ/Wm, which is significant for enhancing dynamic range and responsivity. This study can potentially lead to the development of highly sensitive microwave detectors in the sub-GHz region.