报告题目：Investigation of Interfacial Magnetic Phenomena by Polarized Neutrons and X-rays
报 告 人：Yaohua Liu，Materials Science Division, Argonne National Laboratory
报告时间：2014年8月22日14：00
报告地点：物理系三楼报告厅
报告摘要：Functionalities in complex magnetic heterostructures frequently arise from emergent interfacial phenomena, which require detailed characterization of buried interfaces to reveal the underlying physics. To this respect, interface-sensitive neutron and x-ray techniques are powerful tools to unravel the critical structure-property relationships in magnetic heterostructures. Particularly, x-ray reflectometry (XRR) and polarized neutron reflectometry (PNR) can determine the depth profiles of the chemical structure and the magnetization vector; while X-ray absorption (XAS), X-ray magnetic dichroism (XMD) and linear dichroism (XLD) provide element-specific information on the charge, spin and orbital degrees of freedom. This talk features some of my recent work. (I) Effects of induced magnetization on charge transport at layered oxide interfaces [1,2]. (II) Electric-field control of magnetism in ferromagnetic transition metals [3] and complex oxides [4]. (III) Intrinsic magnetic properties of interfacial phases in exchange-spring magnets [5] and utilization of exchange-spring magnets for investigating ferromagnetism-superconductivity proximity effects [6]. (IV) Interfacial magnetization of highly spin-polarized perovskites and double perovskites [7, 8]. Work at Argonne was supported by the DOE, Office of Science, MSE.
[1] Yaohua Liu et al., Emergent spin filter at a ferromagnetic and insulating layered oxide interface, Phys. Rev. Lett. 111, 247203 (2013).
[2] Yaohua Liu et al., Effect of inteface-induced exchange field on cuprate-manganite spin switches, Phys. Rev. Lett. 108, 207205 (2012).
[3] C. Bi, Yaohua Liu et al., Giant non-volatile voltage-control of magnetism with full reversibility (unpublished).
[4] F.A. Cuellar, Y.H. Liu et al., Reversible electric-field control of magnetization at oxide interfaces, Nat. Commun., 5, 4215 (2014).
[5] Yaohua Liu et al., Magnetic structure in Fe/Sm-Co exchange spring bilayers with intermixed interfaces, Phy. Rev. B 83, 174418 (2011).
[6] L.Y. Zhu, Yaohua Liu et al., Unanticipated proximity behavior in ferromagnet/superconductor heterostructures with controlled magnetic non-collinearity, Phys. Rev. Lett. 110, 177001 (2013).
[7] Yaohua Liu et al., Effects of strain and buffer layer on the interfacial magnetization of Sr2CrReO6 films determined by polarized neutron reflectometry, arXiv:1406.7351. [8] Mark Huijben, Yaohua Liu et al., Enhanced local magnetization by interface engineering in perovskite-type correlated oxide heterostructures (unpublished).
