Extreme Sensitivity of the Spin-Splitting and 0.7 Anomaly to Confining Potential in One-Dimensional Nanoelectronic Devices (original) (raw)
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Spin-based electronics or 'spintronics' has been a topic of interest for over two decades. Electronic devices based on the manipulation of the electron spin are believed to offer the possibility of very small, non-volatile and ultrafast devices with very low power consumption. Since the proposal of a spin-field-effect transistor (SpinFET) by Datta and Das in 1990, many attempts have been made to achieve spin injection, detection and manipulation in semiconductor materials either by incorporating ferromagnetic materials into device architectures or by using external magnetic fields. This approach has significant design complexities, partly due to the influence of stray magnetic fields on device operation. In addition, magnetic electrodes can have magneto-resistance and spurious Hall voltages that can complicate device performance. To date, there has been no successful report of a working Datta-Das SpinFET. Over the last few years we have investigated an all-electric means of manipulating spins, one that only relies on electric fields and voltages and not on ferromagnetic materials or external magnetic fields. We believe we have found a pathway toward this goal, using in-plane side-gated quantum point contacts (QPCs) that rely on lateral spin-orbit coupling to create spin polarization. In this paper we discuss several aspects of our work, beginning with our finding what we believe is nearly complete spin-polarization in InAs QPCs by purely electrical means, our theoretical work to understand the basic mechanisms leading to that situation (asymmetric lateral confinement, lateral spin-orbit coupling and a strong e-e interaction), and our recent work extending the effort to GaAs and to dual QPC systems where one QPC acts as a polarizer and the other as an analyzer.
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Spontaneous spin polarization in GaAs/AlGaAs split-gate heterostructures
Microelectronics Journal, 2005
The spontaneous spin polarization of a quantum point contact (QPC) formed by the lateral confinement of a high-mobility twodimensional electron gas in a GaAs/AlGaAs split-gate heterostructure is investigated. We present self-consistent calculations of the electronic structure of the QPC using the spin-polarized density functional formalism of Kohn and Sham. Spin polarization occurs at low electron densities and exchange potential is found to be the dominant mechanism driving the local polarization within the QPC. We compute the conductance using the cascading scattering matrix approach and observe the conductance anomaly at w0.7 (2e 2 /h). q