# Quantum critical scaling of the conductivity tensor at the metal-insulator transition in Nb$_{1-x}$Ti$_{x}$N

## TL;DR

This study reveals quantum critical behavior in the conductivity tensor at the metal-insulator transition in Nb$_{1-x}$Ti$_{x}$N, challenging traditional paradigms and aligning with recent theoretical models.

## Contribution

It provides the first detailed experimental evidence of quantum criticality in the full conductivity tensor across a continuous MIT in this alloy system.

## Key findings

- Quantum criticality observed in conductivity tensor
- Alignment with theoretical predictions of band-splitting MIT
- Evidence against conventional disorder or Mott transition

## Abstract

In contrast to the Landau paradigm, a metal-insulator transition (MIT), driven purely by competition between itinerance and localization and unaccompanied by any conventional (e.g, magnetic) order-disorder instabilities, admits no obvious local order parameter. Here, we present a detailed analysis of the quantum criticality in magneto-transport data on the alloy Nb$_{1-x}$Ti$_{x}$N across a Ti-doping-driven a MIT. We demonstrate, for the first time, clear and novel quantum criticality reflected in the full conductivity tensor across the MIT. Wide ranging, comprehensive accord with recent theoretical predictions strongly suggests that these unanticipated findings are representative of a continuous MIT of the band-splitting type, rather than a conventional Anderson disorder or a "pure" correlation-driven first-order Mott type.