活动主题：自旋芯片与技术全国重点实验室名师讲堂第三期
活动类型：学术交流
举办单位：自旋芯片与技术全国重点实验室/微纳科学与分析测试协同创新中心
活动时间：2025-05-19 14:30
活动地点：会议中心2001
面向群体：全院师生
主讲嘉宾：
成昭华，中科院物理所研究员，博士生导师，课题组长，国家杰出青年基金获得者，中科院百人计划入选者。1990年和1993年先后获得兰州大学学士和硕士学位，1996年获得中国科学院物理研究所凝聚态物理博士学位。1996-2000 年，分别在德国马普金属研究所和加拿大Dalhousie大学物理系从事博士后研究。主要从事磁性纳米结构与飞秒磁性研究。在Adv. Mater., Phys. Rev. Lett. Nature Comm。， Nano. Lett., PNAS, Phys. Rev.B,.等国际主要学术刊物上发表论文300余篇，发表的论文中被他人引用5000余次, 国际学术会议特邀报告30余次，申请国家发明专利3项。获第九届中国青年科技奖，北京市科学技术一等奖，1997年中国物理学会叶企孙物理奖、国家教委科技进步二等奖。目前主要学术兼职包括中国电子学会理事、会士、应用磁学分会主任委员，中国稀土学会稀土永磁专业委员会副主任委员，中国核物理学会穆斯堡尔专业委员会副主任委员和IEEE Magnetic Society Senior Member等。
内容摘要：
Anisotropic spin relaxation is crucial for advancing materials science, spintronics, and quantum technologies. The spin pumping in ferromagnet/nonmagnetic materials (FM/NM) heterostructures is an effective technique to inject spin current into NM, which provides the possibility of ultrafast, low-power consumption spintronic devices. Previous work demonstrates that the high order terms in k⋅p theory can induce a large warping effect, and consequently snowflake-like Fermi contour in topological insulator (TI). Unfortunately, the effect of warped topological surface state (TSS) on pure spin absorption in FM/TI heterostructures is completely unknown.
In this talk, I will present anisotropic Gilbert damping in Fe/α-GeTe bilayers. By comparing the angle-resolved photoemission spectrum of α-GeTe (5 nm) with that of α-GeTe (30 nm), we confirm that the six-fold anisotropic damping of Fe/α-GeTe originates mainly from the six-fold symmetric band splitting of α-GeTe. Moreover, by considering strength of spin accumulation, we identified a mechanism for the anisotropic absorption of spin current in a FM/TI heterostructure with large warping effect. If the density of state (DOS) of TSS dominates at the Fermi surface, the warping effect results in an anisotropic Gilbert damping at nanosecond timescale and almost isotropic ultrafast demagnetization time at femtosecond timescale. Our work provides a more intuitional way to understand the spin transfer mechanism, and lays the groundwork for advancing anisotropic spintronics.
联系人：自旋芯片与技术全国重点实验室/微纳科学与分析测试协同创新中心，张伟
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