Superconducting and Normal State Properties of Neutron Irradiated MgB2

TL;DR

This study investigates how neutron irradiation and subsequent annealing affect the superconducting and normal state properties of MgB2, demonstrating tunable Tc and recovery of material properties through controlled processing.

Contribution

It provides a systematic analysis of how irradiation and annealing parameters influence MgB2's superconducting transition temperature and lattice structure, enabling property tuning.

Findings

Tc can be tuned between 5 and 39 K through irradiation and annealing.

Higher annealing temperatures and longer times recover Tc and reduce resistivity.

Lattice parameters systematically recover with annealing.

Abstract

We have performed a systematic study of the evolution of the superconducting and normal state properties of neutron irradiated MgB$_2$ wire segments as a function of fluence and post exposure annealing temperature and time. All fluences used suppressed the transition temperature, Tc, below 5 K and expanded the unit cell. For each annealing temperature Tc recovers with annealing time and the upper critical field, Hc2(T=0), approximately scales with Tc. By judicious choice of fluence, annealing temperature and time, the Tc of damaged MgB2 can be tuned to virtually any value between 5 and 39 K. For higher annealing temperatures and longer annealing times the recovery of Tc tends to coincide with a decrease in the normal state resistivity and a systematic recovery of the lattice parameters.