We theoretically studied the thermoelectric transport properties of a strongly correlated quantum dot system in the presence of the Kondo effect based on accurate numerical evaluations using the hierarchical equations...We theoretically studied the thermoelectric transport properties of a strongly correlated quantum dot system in the presence of the Kondo effect based on accurate numerical evaluations using the hierarchical equations of motion approach.The thermocurrent versus gate voltage shows a distinct sawtooth line-shape at high temperatures.In particular,the current changes from positive(hole charge)to negative(particle charge)in the electron number N=1 region due to the Coulomb blockade effect.However,at low temperatures,where the Kondo effect occurs,the thermocurrent’s charge polarity reverses,along with a significantly enhanced magnitude.As anticipated,the current sign can be analyzed by the occupation difference between particle and hole.Moreover,the characteristic turnover temperature can be further defined at which the influences of the Coulomb blockade and Kondo resonance are in an effective balance.Remarkably,the identified characteristic turnover temperature,as a function of the Coulomb interaction and dot-lead coupling,possessed a much higher value than the Kondo temperature.When a magnetic field is applied,a spin-polarized thermocurrent can be obtained,which could be tested in future experiments.展开更多
基金the National Natural Science Foundation of China(Grant Nos.11804245,11747098,11504017,11774418,11674139,11834005,21633006,and U1930402)the China Postdoctoral Science Foundation(Grant No.2019M660431)the Program for the Innovative Talents of Taiyuan Institute of Technology。
文摘We theoretically studied the thermoelectric transport properties of a strongly correlated quantum dot system in the presence of the Kondo effect based on accurate numerical evaluations using the hierarchical equations of motion approach.The thermocurrent versus gate voltage shows a distinct sawtooth line-shape at high temperatures.In particular,the current changes from positive(hole charge)to negative(particle charge)in the electron number N=1 region due to the Coulomb blockade effect.However,at low temperatures,where the Kondo effect occurs,the thermocurrent’s charge polarity reverses,along with a significantly enhanced magnitude.As anticipated,the current sign can be analyzed by the occupation difference between particle and hole.Moreover,the characteristic turnover temperature can be further defined at which the influences of the Coulomb blockade and Kondo resonance are in an effective balance.Remarkably,the identified characteristic turnover temperature,as a function of the Coulomb interaction and dot-lead coupling,possessed a much higher value than the Kondo temperature.When a magnetic field is applied,a spin-polarized thermocurrent can be obtained,which could be tested in future experiments.
