The ratio of normal state to superconducting state of spin lattice relaxation rate of unconventional superconductors

TL;DR

This paper derives a simple expression for the ratio of spin lattice relaxation rates in normal and superconducting states of unconventional superconductors, revealing the presence of coherence peaks contrary to previous beliefs.

Contribution

It introduces a new analytical expression for relaxation rate ratios in unconventional superconductors, including d-wave, p-wave, and 3He A-phase, supported by numerical analysis.

Findings

Coherence peaks are observed in unconventional superconductors.

The derived ratio expression aligns with numerical results.

Unconventional superconductors can exhibit coherence peaks, challenging previous assumptions.

Abstract

In this research, we derive a simple expression for the ratio of normal state superconducting state of spin lattice relaxation rate of unconventional superconductors from the BCS weak-coupling equation. The unconventional superconductors we consider have three types of order parameters as d-wave, 3He A-phase and p-wave 3-dimensional order parameter that had been done before by Parker and Haas[7].After using some numerical approximations and some boundary conditions, we can find the ratio of normal state to superconducting state of spin lattice relaxation rate in power series of temperature dependent order parameters and temperature. Our numerical calculations show the coherence peak below critical temperature clearly that are consistent with Parker and Haas[7]. These results do not agree with the believed that the coherence peak is the only property of s-wave superconductor. However from our calculation, we can conclude that the unconventional superconductors can show the coherence peaks.