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search.filters.applied.f.access: openAccess × Subject: spintronics ×

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    Transient spin injection efficiencies at ferromagnet/metal interfaces
    (Weinheim : Wiley-VCH, 2022-10-19) Elliott, Peter; Eschenlohr, Andrea; Chen, Jinghao; Shallcross, Sam; Bovensiepen, Uwe; Dewhurst, John Kay; Sharma, Sangeeta
    Spin injection across interfaces driven by ultrashort optical pulses on femtosecond timescales constitutes a new way to design spintronics applications. Targeted utilization of this phenomenon requires knowledge of the efficiency of non-equilibrium spin injection. From a quantitative comparison of ab initio time-dependent density functional theory and interface-sensitive, time-resolved non-linear optical experiment, the spin injection efficiency (SIE) at the Co/Cu(001) interface is determined, and its microscopic origin, i.e., the influence of spin-orbit coupling and the interface electronic structure, is discussed. Moreover, we theoretically predict that the SIE at ferromagnetic–metal interfaces can be optimized through laser pulse and materials parameters, namely the fluence, pulse duration, and substrate material.
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    Optical properties and electrical transport of thin films of terbium(III) bis(phthalocyanine) on cobalt
    (Frankfurt, M. : Beilstein-Institut zur Förderung der Chemischen Wissenschaften, 2014) Robaschik, Peter; Siles, Pablo F.; Bülz, Daniel; Richter, Peter; Monecke, Manuel; Fronk, Michael; Klyatskaya, Svetlana; Grimm, Daniel; Schmidt, Oliver G.; Ruben, Mario; Zahn, Dietrich R.T.; Salvan, Georgeta
    The optical and electrical properties of terbium(III) bis(phthalocyanine) (TbPc2) films on cobalt substrates were studied using variable angle spectroscopic ellipsometry (VASE) and current sensing atomic force microscopy (cs-AFM). Thin films of TbPc2 with a thickness between 18 nm and 87 nm were prepared by organic molecular beam deposition onto a cobalt layer grown by electron beam evaporation. The molecular orientation of the molecules on the metallic film was estimated from the analysis of the spectroscopic ellipsometry data. A detailed analysis of the AFM topography shows that the TbPc2 films consist of islands which increase in size with the thickness of the organic film. Furthermore, the cs-AFM technique allows local variations of the organic film topography to be correlated with electrical transport properties. Local current mapping as well as local I–V spectroscopy shows that despite the granular structure of the films, the electrical transport is uniform through the organic films on the microscale. The AFMbased electrical measurements allow the local charge carrier mobility of the TbPc2 thin films to be quantified with nanoscale resolution.
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    Giant multiferroic effects in topological GeTe-Sb2Te3 superlattices
    (Milton Park : Taylor & Francis, 2015) Tominaga, Junji; Kolobov, Alexander V.; Fons, Paul J.; Wang, Xiaomin; Saito, Yuta; Nakano, Takashi; Hase, Muneaki; Murakami, Shuichi; Herfort, Jens; Takagaki, Yukihiko
    Multiferroics, materials in which both magnetic and electric fields can induce each other, resulting in a magnetoelectric response, have been attracting increasing attention, although the induced magnetic susceptibility and dielectric constant are usually small and have typically been reported for low temperatures. The magnetoelectric response usually depends on d-electrons of transition metals. Here we report that in [(GeTe)2(Sb2Te3)l]m superlattice films (where l and m are integers) with topological phase transition, strong magnetoelectric response may be induced at temperatures above room temperature when the external fields are applied normal to the film surface. By ab initio computer simulations, it is revealed that the multiferroic properties are induced due to the breaking of spatial inversion symmetry when the p-electrons of Ge atoms change their bonding geometry from octahedral to tetrahedral. Finally, we demonstrate the existence in such structures of spin memory, which paves the way for a future hybrid device combining nonvolatile phase-change memory and magnetic spin memory.