Bulletin of the American Physical Society
2006 APS March Meeting
Monday–Friday, March 13–17, 2006; Baltimore, MD
Session R3: Lateral Spin Transport |
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Sponsoring Units: DCMP Chair: Chia-Ling Chien, Johns Hopkins University Room: Baltimore Convention Center Ballroom I |
Wednesday, March 15, 2006 2:30PM - 3:06PM |
R3.00001: Spin injection, diffusion and detection in lateral spin valves Invited Speaker: Metallic heterostructures involving ferromagnetic metals (FM) and non-magnetic metals (NM) offer very rich spintronic phenomena, such as giant magnetoresistance and spin-transfer torque. Recently, new interests have been found in heterostructures that feature lateral variation of materials. The motivation originates from the possibility of lateral integration of future spintronic devices and the advantage of extra degrees of freedom in controlling spin accumulation offered by lateral structures. In this work, we demonstrate non- local spin injection and detection in lateral spin valves. A lateral spin valve consists of a NM nanowire connected with two FM electrodes, one as the spin injector and the other as the spin detector. The measurement configurations are arranged in such a way that the current injection circuit and voltage detection circuit are separated, and so are the charge current and the spin current. A pure spin current without charge flow can be obtained in lateral spin valves, and the detected spin signal exhibits very large percentage change. The spin accumulation in lateral spin valves strongly depends on the spin diffusion length of the NM and the injection polarization of FM/NM interface, both of which can be determined by measuring a series of spin valves with different injector detector separations. We have determined the spin diffusion lengths and injection polarizations for Py/Au/Py and Co/Cu/Co lateral spin valves, fabricated by different techniques. The differences of these quantities in two systems will be discussed. This work is done in collaboration with Axel Hoffmann, Sam Jiang, John Pearson, and Sam Bader, and supported by U.S. DOE Office of Basic Energy Science-Materials Science under contract No. W-31- 109-ENG-38. [Preview Abstract] |
Wednesday, March 15, 2006 3:06PM - 3:42PM |
R3.00002: Dynamics of lateral magnetoelectronic thin-film nanostructures Invited Speaker: Hybrid nanostructures made from ferromagnetic and normal metals come in two main flavors: perpendicular multilayer nanopillars and lateral thin film devices. Current-induced magnetization dynamics have until now mainly been studied in perpendicular structures. However, lateral devices have several advantages compared to perpendicular ones, such as relative ease to study multi-terminal configurations and to directly observe the magnetic order parameter. In this talk I will discuss the magnetization dynamics of lateral thin-film structures in the framework of magnetoelectronic circuit theory. The research has been done in collaboration with Xuhui Wang, Yaroslav Tserkovnyak, Arne Brataas, Bart van Wees, Axel Hoffmann, and Teruo Ono. [Preview Abstract] |
Wednesday, March 15, 2006 3:42PM - 4:18PM |
R3.00003: Spin-polarized tunneling and spin diffusion in sub-micron lateral spin-transistors Invited Speaker: Much effort has been devoted to understand how the electron spin is transferred through interfaces and to identify the fundamental processes that suppress the spin polarization. Spin- transistors with the Johnson and Silsbeeās geometry are a unique tool to study these phenomena. In these devices, a spin- polarized current is injected into a non-magnetic metal using a tunnel junction in combination with a ferromagnet (FM), which acts as a spin source. The polarized current results in non- equilibrium spin populations in the non-magnetic metal, which are detected as voltages using a second FM. Fabricated aluminum- based devices with spin transresistances as high as 2 Ohm allow us to study spin-flip scattering mechanisms and spin-polarized tunneling. The tunneling polarization at zero bias is compared with the one estimated with the Meservey and Tedrow technique in the same sample. In addition, as the spin-transistor measurements can be extended to finite voltages and high temperatures, new valuable information is obtained on the character and polarization of the electrons that tunnel out of or into the ferromagnetic source. Surprisingly, the polarization is found to be strongly bias-dependent and asymmetric around zero bias. The origin of these phenomena is analyzed. [Preview Abstract] |
Wednesday, March 15, 2006 4:18PM - 4:54PM |
R3.00004: Spin-torque effects due to pure spin currents in lateral geometries Invited Speaker: Spin injection into the ferromagnetic materials induces a spin torque due to the spin angular momentum transfer between the conduction electron spin and the localized magnetic moment. The magnetization reversal of a nano-scale ferromagnet thereby takes place when the spin polarized current is injected into it. This has been demonstrated using metallic nanopillar devices consisting of magnetic multilayered systems with the spin polarized current flowing perpendicular to the plane. The spin torque mentioned above is known to be proportional to the spin current density. Therefore not the charge current causing the Joule heat but the spin current is essential to realize efficient magnetization reversal due to the spin torque. Thus non-local spin injection technique is employed to realize such a reversal. Here we discuss our resent results on the magnetization reversal due to non-local spin injection into a nano-scale ferromagnetic particle in a lateral ferromagnetic/nonmagnetic hybrid device [1]. \newline \newline [1] T. Kimura and Y. Otani cond-mat/0508559 submitted to PRL. [Preview Abstract] |
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