Mesoscopic quantum effects in a bad metal, hydrogen-doped vanadium dioxide

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Standard theories of quantum corrections to electronic conduction apply to highly conductive materials.
• Phenomena like weak localization magnetoresistance (WLMR) are well-explained in metals and doped semiconductors.
• Vanadium dioxide (VO₂) exhibits a metal-insulator transition, but doping can alter its properties.

Purpose of the Study:

• To investigate quantum transport phenomena in hydrogen-doped vanadium dioxide (HₓVO₂).
• To explore the applicability of standard quantum correction theories to poor metals.
• To understand the influence of doping and strain on mesoscopic quantum effects in HₓVO₂.

Main Methods:

• Fabrication of epitaxial thin films, single-crystal nanobeams, and nanosheets of HₓVO₂.
• Experimental measurement of weak localization magnetoresistance (WLMR) and conductance fluctuations.
• Analysis of the observed phenomena in relation to material properties like high resistivity and doping levels.

Main Results:

• Apparent WLMR and conductance fluctuations were observed in HₓVO₂, a poor metal.
• The observed phenomena persisted across different material forms (films, nanobeams, nanosheets).
• Quantitative analysis of WLMR proved challenging due to the material's high resistivity and deviation from the Mott-Ioffe-Regel limit.

Conclusions:

• The study demonstrates mesoscopic quantum effects in a poor metal, challenging existing theoretical frameworks.
• The findings suggest that standard analyses of WLMR may not be suitable for materials with high resistivity.
• New approaches are needed to assess and analyze quantum phenomena in poor metallic systems like HₓVO₂.