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首页> 外文期刊>Physical review >Temperature-dependent dynamical nuclear polarization bistabilities in double quantum dots in the spin-blockade regime
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Temperature-dependent dynamical nuclear polarization bistabilities in double quantum dots in the spin-blockade regime

机译：自旋封锁体系中双量子点中温度相关的动态核极化双稳态

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摘要

The interplay of dynamical nuclear polarization (DNP) and leakage current through a double quantum dot in the spin-blockade regime is analyzed. A finite DNP is built up due to a competition between hyperfine (HF) spin-flip transitions and another inelastic escape mechanism from the triplets, which block transport. We focus on the temperature dependence of the DNP for zero energy detuning (i.e., equal electrostatic energy of one electron in each dot and a singlet in the right dot). Our main result is the existence of a transition temperature, below which the DNP is bistable, so a hysteretic leakage current versus external magnetic field B appears. This is studied in two cases: (ⅰ) close to the crossing of the three triplet energy levels near B = 0, where spin-blockade is lifted due to the inhomogeneity of the effective magnetic field from the nuclei. (ⅱ) At higher B-fields, where the two spin-polarized triplets simultaneously cross two different singlet energy levels. We develop simplified models leading to different transition temperatures T_(cTT) and T_(cST) for the crossing of the triplet levels and the singlet-triplet level crossings, respectively. We find T_(cTT) analytically to be given solely by the HF couplings, whereas T_(cST) depends on various parameters and T_(cST)＞ T_(cTT) The key idea behind the existence of the transition temperatures at zero energy detuning is the suppression of energy absorption compared to emission in the inelastic HF transitions. Finally, by comparing the rate equation results with Monte Carlo simulations, we discuss the importance of having both HF interaction and another escape mechanism from the triplets to induce a finite DNP.
机译：分析了自旋封锁机制中动态核极化（DNP）与通过双量子点的泄漏电流之间的相互作用。由于超细（HF）自旋翻转转变与三重态的另一种非弹性逃逸机制之间的竞争而建立了有限的DNP，从而阻碍了运输。我们专注于DNP对零能量失谐的温度依赖性（即每个点一个电子和右点一个单线态的静电能量相等）。我们的主要结果是存在一个过渡温度，在该温度以下，DNP是双稳态的，因此出现了相对于外部磁场B的磁滞漏电流。在两种情况下对此进行了研究：（ⅰ）接近B = 0附近的三个三重态能级的交点，其中由于来自核的有效磁场的不均匀性，自旋阻断被解除。 （ⅱ）在较高的B场处，两个自旋极化三胞胎同时穿过两个不同的单重态能级。我们开发了简化的模型，分别导致三重态水平交叉和单重态-三重峰水平交叉产生不同的转变温度T_（cTT）和T_（cST）。我们发现T_（cTT）仅由HF耦合给出，而T_（cST）取决于各种参数，并且T_（cST）＞ T_（cTT）在零能量失谐下存在转变温度的关键思想是与非弹性HF跃迁相比，抑制了能量吸收。最后，通过将速率方程结果与蒙特卡洛模拟进行比较，我们讨论了同时具有HF相互作用和三重态的另一种逃逸机制来诱导有限DNP的重要性。

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  • 来源
    《Physical review》 |2013年第3期|035317.1-035317.24|共24页
  • 作者

    Anders Mathias Lunde; Carlos Lopez-Monis; Ioanna A. Vasiliadou; Luis L. Bonilla; Gloria Platero;

  • 作者单位

    Institute de Ciencia de Materiales de Madrid, CSIC, 28049 Cantoblanco, Madrid, Spain;

    Institute de Ciencia de Materiales de Madrid, CSIC, 28049 Cantoblanco, Madrid, Spain,Institute for Theoretical Physics, University of Regensburg, D-93040 Regensburg, Germany;

    G. Millan Institute, Fluid Dynamics, Nanoscience and Industrial Mathematics, Universidad Carlos Ⅲ de Madrid, Spain,Materials Science and Engineering and Chemical Engineering Department, Universidad Carlos Ⅲ de Madrid, Spain;

    G. Millan Institute, Fluid Dynamics, Nanoscience and Industrial Mathematics, Universidad Carlos Ⅲ de Madrid, Spain,Unidad Asociada al Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Cantoblanco, Madrid, Spain;

    Institute de Ciencia de Materiales de Madrid, CSIC, 28049 Cantoblanco, Madrid, Spain;

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  • 关键词

    quantum dots; self-organized systems; nonequilibrium and irreversible thermodynamics; spin relaxation and scattering;

    机译：量子点;自组织系统;非平衡和不可逆的热力学;自旋弛豫和散射;

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