4,161 research outputs found

    Spin-orbit torques acting upon a perpendicularly-magnetized Py layer

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    We show that Py, a commonly-used soft ferromagnetic material with weak anisotropy, can become perpendicularly-magnetized while depositing on Ta buffer layer with Hf or Zr insertion layers (ILs) and MgO capping layer. By using two different approaches, namely harmonic voltage measurement and hysteresis loop shift measurement, the dampinglike spin-orbit torque (DL-SOT) efficiencies from Ta/IL/Py/IL/MgO magnetic heterostructures with perpendicular magnetic anisotropy are characterized. We find that though Ta has a significant spin Hall effect, the DL-SOT efficiencies are small in systems with the Ta/Py interface compared to that obtained from the control sample with the traditional Ta/CoFeB interface. Our results indicate that the spin transparency for the Ta/Py interface is much less than that for the Ta/CoFeB interface, which might be related to the variation of spin mixing conductance for different interfaces

    A Comparative Study on Spin-Orbit Torque Efficiencies from W/ferromagnetic and W/ferrimagnetic Heterostructures

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    It has been shown that W in its resistive form possesses the largest spin-Hall ratio among all heavy transition metals, which makes it a good candidate for generating efficient dampinglike spin-orbit torque (DL-SOT) acting upon adjacent ferromagnetic or ferrimagnetic (FM) layer. Here we provide a systematic study on the spin transport properties of W/FM magnetic heterostructures with the FM layer being ferromagnetic Co20_{20}Fe60_{60}B20_{20} or ferrimagnetic Co63_{63}Tb37_{37} with perpendicular magnetic anisotropy. The DL-SOT efficiency ξDL|\xi_{DL}|, which is characterized by a current-induced hysteresis loop shift method, is found to be correlated to the microstructure of W buffer layer in both W/Co20_{20}Fe60_{60}B20_{20} and W/Co63_{63}Tb37_{37} systems. Maximum values of ξDL0.144|\xi_{DL}|\approx 0.144 and ξDL0.116|\xi_{DL}|\approx 0.116 are achieved when the W layer is partially amorphous in the W/Co20_{20}Fe60_{60}B20_{20} and W/Co63_{63}Tb37_{37} heterostructures, respectively. Our results suggest that the spin Hall effect from resistive phase of W can be utilized to effectively control both ferromagnetic and ferrimagnetic layers through a DL-SOT mechanism

    Tracer kinetic modeling of ¹¹C-acetate applied in the liver with positron emission tomography

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    Author name used in this publication: Dagan FengAuthor name used in this publication: Zheru ChiCentre for Multimedia Signal Processing, Department of Electronic and Information Engineering2003-2004 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
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