Percolative Instabilities and Sparse-Limit Fractality in 1T-TaS$_2$

TL;DR

This study investigates the electrical and fractal properties of the low-temperature metallic phase in 1T-TaS2, revealing percolative instabilities, domain-wall reorganization, and a connection between fractal percolation and electron transport.

Contribution

It uncovers the role of percolation and fractal structures in the non-equilibrium phase transitions of 1T-TaS2, linking electrical instabilities to hierarchical conductive pathways.

Findings

Abrupt switching and negative differential resistance observed.

Fractal dimension Df varies from 0.3 at 10 K to 0.9 at 300 K.

Scaling exponents align with 2D percolation theory.

Abstract

The low-temperature metallic phase of 1T-TaS2 may originate from current- and voltage-driven destabilization of the commensurate charge density wave (CDW) in a strongly correlated Mott insulator, alongside the robust yet rarely realized influence of intrinsic electronic distortions. Electrical pulse-driven transport, combined with second harmonic response, reveals abrupt switching, negative differential resistance (NDR), and multiscale domain-wall reorganization. The free energy analysis identifies a critical order parameter threshold for the Mott-metal transition, with scaling exponents ({\beta} approx 1.3) consistent with 2D percolation. The sparse limit fractal dimension D_{f} approx 0.3 at 10 K, rising to approx 0.9 at 300 K, reflects the hierarchical evolution of the conductive pathways throughout the temperature. These findings establish a direct connection between fractal percolation, pulse-induced instabilities, and correlated electron transport, offering a framework for controlled access to non-equilibrium phase transitions in low-dimensional quantum materials.