Superconducting Properties of Atomic-Disordered Compound MgCNi_3

TL;DR

This study investigates how radiation-induced atomic disorder affects the superconducting properties of MgCNi_3, revealing a decrease in transition temperature and electronic density of states, with recovery after annealing.

Contribution

It provides new insights into the effects of atomic disorder on superconductivity and electronic structure in MgCNi_3, including the impact of irradiation and annealing.

Findings

Superconducting transition temperature T_C decreases from 6.5 K to 2.9 K after irradiation.

Resistivity temperature dependence indicates strong electron-phonon interaction.

Disordering reduces the electronic density of states at the Fermi level, as shown by H_{C_2} behavior.

Abstract

The effect of radiation-induced disordering in a nuclear reactor (fast neutrons fluence \Phi = 5\cdot10^{19} cm^2, T_{\text{irr}} = 340 K) on resistivity \rho, superconducting transition temperature T_C and upper critical field H_{C_2} of polycrystalline MgCNi_3 samples was investigated. It was found that T_C decreases under irradiation from 6.5 to 2.9 K and completely recovers after annealing at 600 ^\circC. Temperature dependences \rho(T) are characteristic of compounds with strong electron-phonon interaction. The dH_{C_2}/dT behaviour testifies to a considerable decrease in density of electronic state at Fermi level N(E_F) in the course of disordering.