Percolation and nanosecond fluctuators in V2O3 films within the metal-insulator transition

Vanadium sesquioxide (V2O3) exhibits a first-order metal-insulator transition (MIT) at 160 K between a low temperature, monoclinic, antiferromagnetic Mott insulator and a high temperature, rhombohedral, paramagnetic, metallic phase. In thin films, due to strain, the transition takes place over a finite temperature range of phase coexistence. Resistive noise measured through electronic transport is a probe of percolation and the fluctuating dynamics of the two-phase domain structure. We measure voltage noise spectra at both low frequencies (up to 100 kHz) and radio frequencies (between 10 MHz and 1 GHz). At low current densities the voltage noise intensity is quadratic in bias current, as expected for resistive fluctuations probed nonperturbatively by the current. The low frequency noise generally resembles flicker-type 1/f^α noise, often taking on the form of Lorentzian noise dominated by a small number of fluctuators as the volume fraction of the insulating phase dominates. Radio frequency noise intensity that is quadratic in the bias current allows identification of resistance fluctuations with lifetimes below 1 ns, approaching timescales seen in non-equilibrium pump-probe studies of the transition. Noise at higher current densities show non-quadratic bias dependence, implying current-driven changes to the domain dynamics. We find quantitative consistency with a model for fluctuations in the percolative fraction, though thermodynamic analysis implies that switching of domains between metal and insulator phases can only happen on spatial scales comparable to a unit cell.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Natural Sciences

Grantor

Rice University

Year dc:date.issued

2020

Author dc:creator

• Chen, LiYang

Advisor dc:contributor.advisor

• Natelson, Douglas

• strongly correlated system
• V2O3
• percolation
• noise

Statement dc:rights

• Copyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1911/109197

OAI identifier oai:identifier

oai:repository.rice.edu:1911/109197