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ABSTRACT: Cobalt/copper nonlocal spin valve devices with AlOx barriers are fabricated for the purpose of spin-transfer with a pure spin current. The submicron planar device consists of a Co spin injector (F1), a Co spin detector (F2), and a Cu channel. The F2 Co electrode is only 2.5 nm thick, but sizable nonlocal spin signals of 2–4 mΩ are measured at 4.2 K. The spin-transfer switching has been achieved with the assistance of a magnetic field. The magnetizations of F1 and F2 electrodes are set to an antiparallel state by sweeping the magnetic field. The magnetic field is then held at a value smaller but close to the switching field of F2. A small dc current (0.1–1 mA) is sufficient to switch F2 into being parallel with F1. Analysis has been done to rule out possible artifacts due to Oersted fields.
Journal of Applied Physics 08/2010; 108(3):033905-033905-4. · 2.17 Impact Factor
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ABSTRACT: Submicron metallic lateral spin valves are fabricated with AlO <sub>x</sub> tunnel junctions as spin injection and detection barriers. The spin polarization is estimated to be ∼20% , determined by both Hanle effect and variations of device dimensions. The polarization is maintained at a large dc injection current density ≫2×10<sup>6</sup> A / cm <sup>2</sup> . Both the spin polarization and spin diffusion length are weakly temperature dependent.
Applied Physics Letters 08/2009; · 3.84 Impact Factor
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ABSTRACT: The spin signals of three Co/Cu/Co nonlocal spin valves have been measured as a function of a dc bias current. Both increases and decreases of spin signals have been observed. The increase in spin signal is attributed to the redistribution of the injection current at a high current density. A shift in effective injection point up to ∼100 nm is estimated. The decrease in spin signals is attributed to structural change of the materials and interfaces due to the prolonged exposure to a high-density current.
Journal of Applied Physics 06/2009; · 2.17 Impact Factor
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ABSTRACT: Magnetization reversals of cobalt nanoparticles induced by spin transfer torque are demonstrated at 4.2 K by a mechanical point-contact made on a Co/Cu/Co trilayer thin film. The top Co layer ( ∼ 0.5 nm) is discontinuous and consists of isolated cobalt nanoparticles with a diameter of <5 nm. The number of nanoparticles underneath a point contact can be controlled by varying the size of the contact. The characteristics of spin transfer switching are qualitatively different for contacts involving a few particles (5–10) and those involving many particles (40–50).
Applied Physics Letters 10/2008; 93(16):162501-162501-3. · 3.84 Impact Factor
