Effect of valence fluctuations on the ground state properties of SmB6

TL;DR

This paper investigates how valence fluctuations in SmB6 cause energy uncertainties in impurity states, leading to a non-traditional ground state with implications for its low-temperature resistivity behavior.

Contribution

It introduces a novel perspective on the ground state of SmB6, emphasizing the role of valence fluctuations and energy uncertainty in impurity states.

Findings

Impurity energies in SmB6 are represented by intervals due to valence fluctuations.

Both occupied and unoccupied impurity states exist above and below the Fermi level at ground state.

This explains the absence of resistivity divergence at low temperatures in SmB6.

Abstract

We argue that because of valence-fluctuation caused dynamical changes (fluctuations) of impurity energies in the impurity band of SmB6, energies of electrons occupying impurity sites can be due to the uncertainty principle only estimated with corresponding uncertainty, so they can be represented by energy intervals of non-zero width. As a conse- quence, both occupied as well as unoccupied states can be found in the impurity band above as well as below Fermi level even in the ground state. Therefore the subsystem of localized charge carriers in the ground state of SmB6 cannot be described by an energy distribution function expected for T = 0 K. This fundamental conclusion adds another reason for absence of resistivity divergence in SmB6 at lowest temperatures, and sheds new light on interpretation of experimental data obtained for SmB6 and similar systems at lowest temperatures.