Assisted tunneling in metals

Author(s)

Luís Roberto Ramos

• Document type: Master's Dissertation
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT)
• Defense date: 1998-04-06

Examining board members

Valter Luiz Líbero; Amir Ordacgi Caldeira; Miled Hassan Youssef Moussa

• Advisor: Valter Luiz Líbero

Abstract

This work shows a model where a spinless ion tunnels between a double potential well in a metal and interacts eletrostatically with the electrons of conduction bando This model was proposed by Kondo in 1976, but he did not consider the possibility of a tunneling caused by a scattering of conduction electron. This process is called assisted tunneling, and in this work, we take it into account. Numerical Renormalization Group is used to diagonalize the Hamiltonian representing the model. We are showing here curves of specific heat as a function of temperature in the case where there is no assisted tunneling and in the case where it is present. This work also shows that for an appropriate choice of parameters this model maps in the famous Kondo Hamiltonian for a magnetic impurity in metal. Finally, we are showing the behavior of the effective tunneling rate as a function of the parameter that represent the assisted tunneling. In special, the results show that the rate may be, in some cases, larger that the bare tunneling rate. (AU)