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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Quantum interference effect in electron tunneling through a quantum-dot-ring spin valv | Ma et al. Nanoscale Research Letters 2011 6 265 http www.nanoscalereslett.eom content 6 1 265 o Nanoscale Research Letters a SpringerOpen Journal NANO IDEA Open Access Quantum interference effect in electron tunneling through a quantum-dot-ring spin valve Jing-Min Ma Jia Zhao Kai-Cheng Zhang Ya-Jing Peng and Feng Chi Abstract Spin-dependent transport through a quantum-dot QD ring coupled to ferromagnetic leads with noncollinear magnetizations is studied theoretically. Tunneling current current spin polarization and tunnel magnetoresistance TMR as functions of the bias voltage and the direct coupling strength between the two leads are analyzed by the nonequilibrium Green s function technique. It is shown that the magnitudes of these quantities are sensitive to the relative angle between the leads magnetic moments and the quantum interference effect originated from the inter-lead coupling. We pay particular attention on the Coulomb blockade regime and find the relative current magnitudes of different magnetization angles can be reversed by tuning the inter-lead coupling strength resulting in sign change of the TMR. For large enough inter-lead coupling strength the current spin polarizations for parallel and antiparallel magnetic configurations will approach to unit and zero respectively. PACS numbers Introduction Manipulation of electron spin degree of freedom is one of the most frequently studied subjects in modern solid state physics for both its fundamental physics and its attractive potential applications 1 2 . Spintronics devices based on the giant magnetoresistance effect in magnetic multi-layers such as magnetic field sensor and magnetic hard disk read heads have been used as commercial products and have greatly influenced current electronic industry. Due to the rapid development of nanotechnology recent much attention has been paid on the spin injection and tunnel magnetoresistance TMR effect in tunnel junctions made of semiconductor spacers sandwiched .
