近日，荷兰拉德堡大学分子与材料研究所的C. S. Davies及其研究团队取得一项新进展。经过不懈努力，他们利用超快巴尼特效应实现磁化的声子开关。相关研究成果已于2024年4月10日在国际权威学术期刊《自然》上发表。

该研究团队成功证明，通过超快巴尼特效应实现的自发磁化，能够借助顺磁性衬底中圆偏振光学声子的共振激发，永久地改变安装在衬底上的异质结构的磁性状态。由于声子的手性决定了磁开关的方向，超快巴尼特效应为超快非局部控制磁有序提供了一种选择性且潜在的通用方法。

据悉，巴内特效应在历史上阐明了净磁矩为零的惯性体在机械旋转时如何自发磁化。而最新实验突破显示，超短激光脉冲能在数百飞秒内瓦解有序铁磁体的磁化，使自旋失去角动量，转变为圆偏振光学声子，这是超快爱因斯坦-德哈斯效应的一环。然而，关于如何利用这种晶格高频振动在邻近磁性介质中实现磁化往复开关的潜力，尚待实验进一步探索。

附：英文原文

Title: Phononic switching of magnetization by the ultrafast Barnett effect

Author: Davies, C. S., Fennema, F. G. N., Tsukamoto, A., Razdolski, I., Kimel, A. V., Kirilyuk, A.

Issue&Volume: 2024-04-10

Abstract: The historic Barnett effect describes how an inertial body with otherwise zero net magnetic moment acquires spontaneous magnetization when mechanically spinning. Breakthrough experiments have recently shown that an ultrashort laser pulse destroys the magnetization of an ordered ferromagnet within hundreds of femtoseconds, with the spins losing angular momentum to circularly polarized optical phonons as part of the ultrafast Einstein–de Haas effect. However, the prospect of using such high-frequency vibrations of the lattice to reciprocally switch magnetization in a nearby magnetic medium has not yet been experimentally explored. Here we show that the spontaneous magnetization gained temporarily by means of the ultrafast Barnett effect, through the resonant excitation of circularly polarized optical phonons in a paramagnetic substrate, can be used to permanently reverse the magnetic state of a heterostructure mounted atop the said substrate. With the handedness of the phonons steering the direction of magnetic switching, the ultrafast Barnett effect offers a selective and potentially universal method for exercising ultrafast non-local control over magnetic order.

DOI: 10.1038/s41586-024-07200-x

Source: https://www.nature.com/articles/s41586-024-07200-x