Mn-site doping and its effect on inverted hysteresis and thermomagnetic irreversibility behavior of antiferromagnetic Mn$_5$Si$_3$ alloy

TL;DR

This study investigates how Mn-site doping with Ni and Cr alters the magnetic phase transitions, hysteresis behavior, and irreversibility in Mn$_5$Si$_3$ alloys, revealing suppression of certain magnetic features with increased doping.

Contribution

It provides new insights into the effects of Ni and Cr doping on the magnetic properties and hysteresis phenomena of Mn$_5$Si$_3$ alloys, which were previously not well understood.

Findings

Doped alloys retain hexagonal structure with phase transitions.

Critical transition temperatures decrease with doping.

Inverted hysteresis and related features vanish at 4% doping.

Abstract

The structural and magnetic behavior of Mn-site doped intermetallic manganese silicide alloys of nominal compositions Mn$_{5-x}$A$_x$Si$_3$ ($x$ = 0.05, 0.1, 0.2 and A = Ni, Cr) have been investigated with a focus to the inverted hysteresis behavior and thermomagnetic irreversibility. Room temperature x-ray powder diffraction data confirm that all the doped alloys crystallize in hexagonal $D8_8$ type structure with space group $P6_3/mcm$. The doped alloys are found to show paramagnetic (PM) - collinear antiferromagnetic (AFM2) - noncollinear antiferromagnetic (AFM1) transitions during cooling from room temperature. A significant decrease in the critical values of both AFM1-AFM2 transition temperatures and fields have been observed with the increasing Ni/Cr concentration. Inverted hysteresis loop, field-induced arrest, and thermomagnetic arrest, the key features of the undoped Mn$_5$Si$_3$ alloy, are found to be significantly affected by the Mn-site doping and eventually vanishes with 4\% doping.