tailieunhanh - báo cáo hóa học: " Efficient spin filter using multi-terminal quantum dot with spin-orbit interaction"

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: Efficient spin filter using multi-terminal quantum dot with spin-orbit interaction | Yokoyama and Eto Nanoscale Research Letters 2011 6 436 http content 6 1 436 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Efficient spin filter using multi-terminal quantum dot with spin-orbit interaction Tomohiro Yokoyama and Mikio Eto Abstract We propose a multi-terminal spin filter using a quantum dot with spin-orbit interaction. First we formulate the spin Hall effect SHE in a quantum dot connected to three leads. We show that the SHE is significantly enhanced by the resonant tunneling if the level spacing in the quantum dot is smaller than the level broadening. We stress that the SHE is tunable by changing the tunnel coupling to the third lead. Next we perform a numerical simulation for a multi-terminal spin filter using a quantum dot fabricated on semiconductor heterostructures. The spin filter shows an efficiency of more than 50 when the conditions for the enhanced SHE are satisfied. PACS numbers Introduction The injection and manipulation of electron spins in semiconductors are important issues for spin-based electronics spintronics. 1 The spin-orbit SO interaction can be a key ingredient for both of them. The SO interaction for conduction electrons in direct-gap semiconductors is written as Hsq hO p X VU r 1 where U r is an external potential and s indicates the electron spin s s 2. The coupling constant l is largely enhanced in narrow-gap semiconductors such as InAs compared with the value in the vacuum 2 . In two-dimensional electron gas 2DEG xy plane in semiconductor heterostructures an electric field perpendicular to the 2DEG U r eEz induces the Rashba SO interaction 3 4 a Hsq h pyơx - pxơy 2 where a eEẢ. The Rashba SO interaction can be tuned by the external electric field or the gate voltage 5-7 . In the spin transistor proposed by Datta and Das 8 electron spins are injected into the 2DEG from a ferromagnet and manipulated by tuning the strength of Rashba SO .