Universality and the thermoelectric transport properties through semiconductor nanostructures

Date

Aug 15, 2013

Time

9:30 AM - 10:15 AM

Speaker

Roberto Emilio Franco Peñaloza

Language

en

Main Topic

Physik

Other Topics

Physik

Host

QSOE13

Description

Lucas E. V. Sala (1), R. Franco (1,2) and L. N. Oliveira (1). 1. Instituto de F\'{\i}sica de S\~ao Carlos, Universidade de S\~ao Paulo, 13560-970 S\~ao Carlos, SP – Brazil. 2. Departamento de F\'{\i}sica, Universidad Nacional de Colombia, A. A 5997, Bogotà – Colombia. We will discuss the temperature-dependent thermoelectric transport properties of semiconductor nanostructures comprising a quantum dot coupled to quantum wires, that is, the thermal dependences of the electrical conductance, thermal conductance and thermopower. The physics of electrical and thermal conduction through the nanostructures is controlled by the antiferromagnetic interaction between the magnetic moment of the dot and the spins of the conduction electrons in the wires. At low temperatures, the conduction electrons tend to screen the dot moment, which originates the Kondo effect. We explore the universality of the thermoelectric properties in the temperature range governed by the Kondo crossover. In this thermal range, general arguments indicate that the temperature dependence of any equilibrium property should be a universal function of the ratio $T/T_K$, where $T_K$ is the Kondo temperature. Experimental work has nevertheless failed to identified universal behavior [1]. On the theoretical front, the zero-bias electrical conductance through a quantum dot embedded in a quantum wire and the conductance through a quantum wire side-coupled to a quantum dot have recently been shown to map linearly onto the universal conductance for the particle-hole symmetric, spin-degenerate Anderson model [2]. Here we extend this result to the other thermoelectric transport properties, the thermopower and the thermal conductance. Our analysis relies on rigorous renormalization-group arguments. Illustrative numerical renormalization-group [3] results will be presented to bring out the physics in our findings. [1] M. Grobis, I. G. Rau, R. M. Potok, H. Shtrikman, and D. Goldaber-Gordon, Phys. Rev. Lett. 100, 246601 (2008) and references therein. [2] A. C. Seridonio, M. Yoshida and L. N. Oliveira, Phys. Rev. B 80, 235317 (2009); 80, 23518 (2009). [3] K. G. Wilson, Rev. Mod. Phys. 47, 773 (1975); R. Bulla, T. Costi, and T. Pruschke, Rev. Mod. Phys. 80, 55 (2007).

Last modified: Aug 15, 2013, 9:56:57 AM