Butterfly-shaped magnetoresistance in van der Waals ferromagnet Fe5GeTe2
Tomoharu Ohta, Masashi Tokuda, Shuichi Iwakiri, Kosuke Sakai, Benjamin Driesen, Yoshinori Okada, Kensuke Kobayashi, Yasuhiro Niimi
Abstract
We have performed magnetoresistance (MR) measurements on van der Waals ferromagnetic devices using quenched- (Q-) and nonquenched- (NQ-) Fe5GeTe2 crystals. A clear butterfly-shaped hysteresis has been observed for thin-film (less than 6 unit-cell layer) Q- and NQ-Fe5GeTe2 devices, but not for thicker film ones. The switching field of the butterfly-shaped MR is consistent with the coercive filed obtained from the Hall measurements. The MR ratio of the butterfly peak reaches about 10% at maximum, which is much larger than that observed with conventional magnetic materials. Such a large MR ratio would be related to magnetic fluctuations due to the complicated magnetic structure in this material.