Time-dependent universal conductance fluctuations in IrO2 nanowires

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Universal Conductance Fluctuations (UCFs) are a quantum interference phenomenon observed in disordered conductors.
• Time-dependent UCFs (TUCFs) are attributed to scattering from mobile defects, offering a probe into dynamic processes within materials.
• Iridium dioxide (IrO2) is a conductive oxide with potential applications in electronics.

Purpose of the Study:

• To investigate the presence and characteristics of TUCFs in single-crystalline iridium dioxide nanowires.
• To determine the temperature dependence of TUCFs and their magnitudes.
• To understand the underlying scattering mechanisms responsible for TUCFs in IrO2 nanowires.

Main Methods:

• Fabrication of single-crystalline iridium dioxide nanowires.
• Low-temperature electrical transport measurements to observe conductance.
• Analysis of conductance fluctuations as a function of time and temperature.
• Comparison of experimental results with existing theories of TUCFs.

Main Results:

• Single-crystalline IrO2 nanowires exhibit TUCFs at cryogenic temperatures, persisting up to approximately 10 K.
• The root-mean-square magnitude of TUCFs increases with decreasing temperature, reaching ~0.1 e²/h at 1.7 K.
• Experimental TUCF characteristics are consistent with the three-dimensional TUCF theory, indicating scattering from mobile defects.

Conclusions:

• Mobile defects in IrO2 nanowires act as dynamic scattering centers, causing TUCFs.
• The electron dephasing length at 1.7 K (~90 nm) is smaller than the nanowire diameter (~180 nm), consistent with observed TUCFs.
• This study demonstrates the utility of TUCFs for probing electron scattering dynamics in conductive nanowires.