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Interfacial Dzyaloshinskii-Moriya interaction, surface anisotropy energy,and spin pumping at spin orbit coupled Ir/Co interface

175   0   0.0 ( 0 )
 Added by Chun-Yeol You
 Publication date 2016
  fields Physics
and research's language is English




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The interfacial Dzyaloshinskii-Moriya interaction (iDMI), surface anisotropy energy, and spin pumping at the Ir/Co interface are experimentally investigated by performing Brillouin light scattering. Contrary to previous reports, we suggest that the sign of the iDMI at the Ir/Co interface is the same as in the case of the Pt/Co interface. We also find that the magnitude of the iDMI energy density is relatively smaller than in the case of the Pt/Co interface, despite the large strong spin-orbit coupling (SOC) of Ir. The saturation magnetization and the perpendicular magnetic anisotropy (PMA) energy are significantly improved due to a strong SOC. Our findings suggest that an SOC in an Ir/Co system behaves in different ways for iDMI and PMA. Finally, we determine the spin pumping effect at the Ir/Co interface, and it increases the Gilbert damping constant from 0.012 to 0.024 for 1.5 nmthick Co.



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170 - Lijun Zhu , Lujun Zhu , Xin Ma 2020
The quantitative roles of the interfacial spin-orbit coupling (SOC) in Dzyaloshinskii-Moriya interaction (DMI) and dampinglike spin-orbit torque ({tau}DL) have remained unsettled after a decade of intensive study. Here, we report a conclusive experiment evidence that, because of the critical role of the interfacial orbital hybridization, the interfacial DMI is not necessarily a linear function of the interfacial SOC, e.g. at Au1-xPtx/Co interfaces where the interfacial SOC can be tuned significantly via strongly composition (x)-dependent spin-orbit proximity effect without varying the bulk SOC and the electronegativity of the Au1-xPtx layer. We also find that {tau}DL in the Au1-xPtx/Co bilayers varies distinctly from the interfacial SOC as a function of x, indicating no important {tau}DL contribution from the interfacial Rashba-Edelstein effect.
In contrast to conventional assumptions, we show that the Dzyaloshinskii-Moriya interaction can be of non-relativistic origin, in particular in materials with a non-collinear magnetic configuration, where non-relativistic contributions can dominate over spin-orbit effects. The weak antiferromagnetic phase of Mn$_{3}$Sn is used to illustrate these findings. Using electronic structure theory as a conceptual platform, all relevant exchange interactions are derived for a general, non-collinear magnetic state. It is demonstrated that non-collinearity influences all three types of exchange interaction and that physically distinct mechanisms, which connect to electron- and spin-density and currents, may be used as a general way to analyze and understand magnetic interactions of the solid state.
The Dzyaloshinskii-Moriya interaction (DMI) has been shown to stabilise Ne{e}l domain walls in magnetic thin films, allowing high domain wall velocities driven by spin current effects. DMI occurs at the interface between ferromagnetic and heavy metal layers with strong spin-orbit coupling, but details of the interaction remain to be understood and the role of proximity induced magnetism (PIM) in the heavy metal is unknown. We report interfacial DMI and PIM in Pt determined as a function of Au and Ir spacer layers in Pt/Co/Au,Ir/Pt. The length-scale for both interactions is sensitive to sub-nanometre changes in the spacer thickness, and they correlate over sub mono-layer spacer thicknesses, but not for thicker spacers. The spacer layer thickness dependence of the Pt PIM for both Au and Ir shows a rapid monotonic decay, while the DMI changes rapidly but has a two-step approach to saturation and continues to change, even after the PIM is lost.
We report on the study of both perpendicular magnetic anisotropy (PMA) and Dzyaloshinskii-Moriya interaction (DMI) at an oxide/ferromagnetic metal (FM) interface, i.e. BaTiO3 (BTO)/CoFeB. Thanks to the functional properties of the BTO film and the capability to precisely control its growth, we are able to distinguish the dominant role of the oxide termination (TiO2 vs BaO), from the moderate effect of ferroelectric polarization in the BTO film, on the PMA and DMI at the oxide/FM interface. We find that the interfacial magnetic anisotropy energy of the BaO-BTO/CoFeB structure is two times larger than that of the TiO2-BTO/CoFeB, while the DMI of the TiO2-BTO/CoFeB interface is larger. We explain the observed phenomena by first-principles calculations, which ascribe them to the different electronic states around the Fermi level at the oxide/ferromagnetic metal interfaces and the different spin-flip processes. This study paves the way for further investigation of the PMA and DMI at various oxide/FM structures and thus their applications in the promising field of energy-efficient devices.
Recently, antiferromagnets have received revived interest due to their significant potential for developing next-generation ultrafast magnetic storage. Here we report dc spin pumping by the acoustic resonant mode in a canted easy-plane antiferromagnet {alpha}-Fe2O3 enabled by the Dzyaloshinskii-Moriya interaction. Systematic angle and frequency dependent measurements demonstrate that the observed spin pumping signals arise from resonance-induced spin injection and inverse spin Hall effect in {alpha}-Fe2O3/metal heterostructures, mimicking the behavior of spin pumping in conventional ferromagnet/nonmagnet systems. The pure spin current nature is further corroborated by reversal of the polarity of spin pumping signals when the spin detector is switched from platinum to tungsten which has an opposite sign of the spin Hall angle. Our results highlight the potential opportunities offered by the low-frequency acoustic resonant mode in canted easy-plane antiferromagnets for developing next-generation, functional spintronic devices.
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