Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden.
Nanotechnology. 2012 Apr 6;23(13):135705. doi: 10.1088/0957-4484/23/13/135705. Epub 2012 Mar 16.
The Hanle effect in InAs/GaAs quantum dots (QDs) is studied under optical orientation as a function of temperature over the range of 150-300 K, with the aim of understanding the physical mechanism responsible for the observed sharp increase of electron spin polarization with increasing temperature. The deduced spin lifetime T(s) of positive trions in the QDs is found to be independent of temperature, and is also insensitive to excitation energy and density. It is argued that the measured T(s) is mainly determined by the longitudinal spin-flip time (T(1)) and the spin dephasing time (T(2)*) of the studied QD ensemble, of which both are temperature independent over the studied temperature range and the latter makes a larger contribution. The observed sharply rising QD spin polarization degree with increasing temperature, on the other hand, is shown to be induced by an increase in spin injection efficiency from the barrier/wetting layer and also by a moderate increase in spin detection efficiency of the QD.
砷化铟/砷化镓量子点中的汉勒效应在光学定向下作为温度的函数进行研究，温度范围为 150-300 K，目的是了解导致观察到的电子自旋极化随温度升高而急剧增加的物理机制。在量子点中，正三价离子的推导自旋寿命 T(s) 被发现与温度无关，并且对激发能量和密度也不敏感。有人认为，测量得到的 T(s) 主要取决于研究的量子点系综的纵向自旋翻转时间（T(1)）和自旋退相时间（T(2)*），这两者在研究的温度范围内均与温度无关，而后者的贡献更大。另一方面，观察到的量子点自旋极化度随温度的急剧上升，被证明是由从势垒/湿层的自旋注入效率的增加以及量子点的自旋检测效率的适度增加引起的。
