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

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 $D{8}_8$ type structure with space group $P{6}_3/mcm$. 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.