Amasha S, Keller A J, Rau I G, Carmi A, Katine J A, Shtrikman Hadas, Oreg Y, Goldhaber-Gordon D
Department of Physics, Stanford University, Stanford, California 94305, USA.
Department of Applied Physics, Stanford University, Stanford, California 94305, USA.
Phys Rev Lett. 2013 Jan 25;110(4):046604. doi: 10.1103/PhysRevLett.110.046604. Epub 2013 Jan 24.
We report measurements of the Kondo effect in a double quantum dot, where the orbital states act as pseudospin states whose degeneracy contributes to Kondo screening. Standard transport spectroscopy as a function of the bias voltage on both dots shows a zero-bias peak in conductance, analogous to that observed for spin Kondo in single dots. Breaking the orbital degeneracy splits the Kondo resonance in the tunneling density of states above and below the Fermi energy of the leads, with the resonances having different pseudospin character. Using pseudospin-resolved spectroscopy, we demonstrate the pseudospin character by observing a Kondo peak at only one sign of the bias voltage. We show that even when the pseudospin states have very different tunnel rates to the leads, a Kondo temperature can be consistently defined for the double quantum dot system.
我们报告了在一个双量子点中对近藤效应的测量结果，其中轨道态充当赝自旋态，其简并性有助于近藤屏蔽。作为两个量子点上偏置电压函数的标准输运光谱显示出电导中的零偏置峰，类似于在单量子点中观察到的自旋近藤效应。打破轨道简并会在引线费米能上下的隧穿态密度中分裂近藤共振，这些共振具有不同的赝自旋特性。使用赝自旋分辨光谱，我们通过仅在偏置电压的一个符号处观察到近藤峰来证明赝自旋特性。我们表明，即使赝自旋态与引线的隧穿速率非常不同，也可以为双量子点系统一致地定义一个近藤温度。
