Understanding how electronic transport evolves from localized to itinerant regimes in correlated cluster solids remains an important challenge in condensed-matter physics. Here we investigate the pressure-dependent transport properties of the lacunar spinel GaNb4Se8, a cluster Mott insulator at ambient conditions. At low pressures, the resistivity follows Efros-Shklovskii variable-range hopping, indicating Coulomb-gap-controlled carrier localization (x ~ 6.1 Angstrom). A crossover toward metallic transport begins near ~ 5 GPa, whereas a crystallographic transition from the cubic phase to a monoclinic C2 phase occurs at significantly higher pressure (~ 20 GPa), establishing a hierarchy characterized by the decoupling of electronic delocalization from structural symmetry change. At higher pressures, superconductivity (xi(0) ~ 80-90 Angstrom) emerges from the correlated metallic regime. These results identify GaNb4Se8 as a platform for studying correlation-controlled transport evolution in cluster-based solids.
@article{arxiv.2604.26203,
title = {From Wavefunction Collapse to Superconductivity: Evolution of the Electronic State in Compressed GaNb4Se8},
author = {Yuejian Wang and Zhongyan Wu and K C Bhupendra and Dongzhou Zhang and Lin Wang and Sanjay V. Khare and Lilian Prodan and Vladimir Tsurkan},
journal= {arXiv preprint arXiv:2604.26203},
year = {2026}
}