We report direct observation of gyromagnetic reversal, which is the sign change of the gyromagnetic ratio in a ferrimagnet insulator Ho3Fe5O12, by using the Barnett effect measurement technique at low temperatures. The Barnett effect is a phenomenon in which magnetization is induced by mechanical rotation through the coupling between rotation and total angular momentum J of electrons. The magnetization of Ho3Fe5O12 induced by mechanical rotation disappears at 135 K and 240 K. The temperatures correspond to the magnetization compensation temperature TM and the angular momentum compensation temperature TA, respectively. Between TM and TA, the magnetization flips over to be parallel against the angular momentum due to the sign change of the gyromagnetic ratio. This study provides an unprecedented technique to explore the gyromagnetic properties.
Observation of gyromagnetic reversal
Masaki Imai, Yudai Ogata, Hiroyuki Chudo, Masao Ono, Kazuya Harii, Mamoru Matsuo, Yuichi Ohnuma, Sadamichi Maekawa, Eiji Saitoh; Observation of gyromagnetic reversal. Appl. Phys. Lett. 30 July 2018; 113 (5): 052402. https://doi.org/10.1063/1.5041464
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