Record high superconducting transition temperature in Ti$_{1-x}$Mn$_x$ alloy with rich magnetic element Mn

TL;DR

This study reports a record high superconducting transition temperature of about 26 K in Ti$_{1-x}$Mn$_x$ alloy under high pressure, challenging the notion that magnetic elements suppress superconductivity.

Contribution

It demonstrates enhanced superconductivity in a Mn-containing alloy under high pressure, with experimental and theoretical analysis revealing unexpected behavior.

Findings

Superconductivity reaches 26 K in Ti$_{1-x}$Mn$_x$ alloy under high pressure.

The upper critical field exceeds the Pauli limit in the mid-pressure regime.

The beta-phase structure remains unchanged with volume contraction under pressure.

Abstract

It is well-known that magnetic moments are very harmful to superconductivity. A typical example is the element Mn whose compounds usually exhibit strong magnetism. Thus, it is very hard to achieve superconductivity in materials containing Mn. Here, we report enhanced superconductivity with the superconducting transition temperature ($T_\text{c}$) up to a record high-value of about 26 K in a beta-phase Ti$_{1-x}$Mn$_x$ alloy containing rich magnetic element Mn under high pressures. This is contrary to the intuition that the magnetic moments always suppress superconductivity. Under high pressures, we also found that in the middle-pressure regime, the Pauli limit of the upper critical field is surpassed. The synchrotron X-ray diffraction data shows an unchanged beta-phase with a continuous contraction of the cell volume, which is well supported by the first-principles calculations. Although the theoretical results based on electron-phonon coupling (EPC) can interpret the $T_\text{c}$ value in a certain pressure region, the monotonic enhancement of superconductivity by pressure cannot seek support from the theory. Our results show a surprising enhancement of superconductivity in Ti$_{1-x}$Mn$_x$ alloy with a considerable Mn content.