Spectroscopy ofd-wave superconductors using DNA as a probing tip.

Area of Science:

• Condensed Matter Physics
• Nanoscience
• Biophysics

Background:

• Andreev reflection is a key phenomenon in superconductivity.
• DNA molecules offer unique one-dimensional transport properties.
• d-wave superconductors possess characteristic midgap surface states.

Purpose of the Study:

• Investigate Andreev reflection in DNA-superconductor systems.
• Demonstrate DNA's utility as a spectroscopic probe for superconductors.
• Analyze the influence of DNA structure and coupling on reflection properties.

Main Methods:

• Simulations using a two-leg ladder model for DNA.
• Modeling DNA as homopolymers.
• Analyzing Andreev reflection probability under varying coupling and bias voltage.

Main Results:

• An increased Andreev reflection probability at zero bias due to d-wave superconductor midgap states.
• Significant enhancement (orders of magnitude) of the zero-bias peak with weakened coupling.
• High sensitivity of reflection probability to voltage bias and d-wave symmetry orientation.
• Quantum interference effects leading to a dip-plateau-peak structure at zero bias.

Conclusions:

• DNA serves as a sensitive probe for d-wave superconductor spectroscopy.
• The observed phenomena are strongly dependent on DNA-superconductor coupling and molecular parameters.
• Inter-strand coupling in DNA influences the zero-bias features, allowing for its evaluation.