Quantum criticality in a Mott pn-junction in an armchair carbon nanotube

TL;DR

This paper predicts quantum-critical behavior in a Mott insulator region of an armchair carbon nanotube pn junction, where conductance scales differently with temperature depending on the electric field, revealing a unique quantum critical point.

Contribution

It introduces the concept of quantum-critical behavior in a Mott insulator within a carbon nanotube pn junction, highlighting a novel conductance scaling and a critical point.

Findings

Conductance G scales to zero or to 4e^2/h as temperature decreases.

Existence of a quantum critical point at a specific electric field E.

Distinct behavior from a simple barrier in a Luttinger liquid.

Abstract

In an armchair carbon nanotube pn junction the p- and n- regions are separated by a region of a Mott insulator, which can backscatter electrons only in pairs. We predict a quantum-critical behavior in such a pn junction. Depending on the junction's built-in electric field E, its conductance G scales either to zero or to the ideal value G=4e^2/h as the temperature T is lowered. The two types of the G(T) dependence indicate the existence, at some special value of E, of an intermediate quantum critical point with a finite conductance G<4e^2/h. This makes the pn junction drastically different from a simple barrier in a Luttinger liquid.