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今井 正樹; 中堂 博之; 松尾 衛; 前川 禎通; 齊藤 英治
Physical Review B, 102(1), p.014407_1 - 014407_5, 2020/07
被引用回数:7 パーセンタイル:34.47(Materials Science, Multidisciplinary)The angular momentum compensation temperature of ferrimagnets has attracted much attention because of high-speed magnetic dynamics near
. We show that NMR can be used to investigate domain wall dynamics near
in ferrimagnets. We performed
Fe-NMR measurements on the ferrimagnet Ho
Fe
O
with
= 245 K. In a multi-domain state, the NMR signal is enhanced by domain wall motion. We found that the NMR signal enhancement shows a maximum at
in the multi-domain state. The NMR signal enhancement occurs due to increasing domain-wall mobility toward
. We develop the NMR signal enhancement model involves domain-wall mobility. Our study shows that NMR in multi-domain state is a powerful tool to determine
, even from a powder sample and it expands the possibility of searching for angular momentum-compensated materials.
今井 正樹; 中堂 博之; 小野 正雄; 針井 一哉; 松尾 衛; 大沼 悠一*; 前川 禎通; 齊藤 英治
Applied Physics Letters, 114(16), p.162402_1 - 162402_4, 2019/04
被引用回数:23 パーセンタイル:70.48(Physics, Applied)We demonstrate that the angular momentum compensation temperature , at which the net angular momentum in the sample disappears, can be controlled in Ho
Fe
O
by partially substituting Dy for Ho. The
can be detected using the Barnett effect, by which mechanical rotation magnetizes an object due to spin-rotation coupling. We found that
increases with the Dy content and clarified that the
of Ho
Dy
Fe
O
coincides with room temperature. The Barnett effect enables us to explore materials applicable to magnetic devices utilizing the angular momentum compensation only by rotating the powder sample at room temperature.
今井 正樹; 緒方 裕大*; 中堂 博之; 小野 正雄; 針井 一哉; 松尾 衛*; 大沼 悠一*; 前川 禎通; 齊藤 英治
Applied Physics Letters, 113(5), p.052402_1 - 052402_3, 2018/07
被引用回数:22 パーセンタイル:66.33(Physics, Applied)We report direct observation of gyromagnetic reversal, which is the sign change of gyromagnetic ratio in a ferrimagnet HoFe
O
, 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
of electrons. The magnetization of Ho
Fe
O
induced by mechanical rotation disappears at 135 K and 240 K. The temperatures correspond to the magnetization compensation temperature
and the angular momentum compensation temperature
, respectively. Between
and
, the magnetization flips over to be parallel against the angular momentum due to the sign change of gyromagnetic ratio. This study provides an unprecedented technique to explore the gyromagnetic properties.
今井 正樹; 中堂 博之; 松尾 衛*; 前川 禎通*; 齊藤 英治
no journal, ,
Ferrimagnets contains multiple types of magnetic ions; their magnetic moments align in opposite direction. In some ferrimagnets, the net angular momentum becomes zero at the angular momentum compensation temperature . We demonstrated the observation of
by using the Barnett effect and NMR.