In-chain tunneling through charge-density-wave nanoconstrictions and break junctions

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Charge-density wave (CDW) conductors exhibit unique electronic properties due to periodic lattice distortions.
• Niobium triselenide (NbSe3) is a quasi-one-dimensional material known for its two distinct CDW transitions.

Purpose of the Study:

• To investigate charge transport mechanisms in nanoscale constrictions of NbSe3.
• To probe the nature of the energy gaps associated with CDW transitions at the nanoscale.

Main Methods:

• Fabrication of longitudinal nanoconstrictions in NbSe3 using focused ion beam (FIB) and mechanically controlled break-junction techniques.
• Measurement of electrical conductance at cryogenic temperatures across the CDW transitions.

Main Results:

• Observed conductance peaks below the CDW transition temperatures (TP1=145 K, TP2=59 K).
• These peaks closely match theoretical predictions for the full CDW gaps (2Delta1, 2Delta2).
• The observed data supports a CDW-CDW tunneling model with energy gap corrugation, inconsistent with back-to-back normal-conductor junction models.

Conclusions:

• The study provides evidence for CDW-CDW tunneling in NbSe3 nanoconstrictions.
• Nanoscale fabrication techniques enable the study of fundamental CDW physics.
• The results highlight the importance of gap corrugation in understanding transport in CDW materials.