Real Space Visualization of Thermomagnetic Irreversibility within Supercooling and Superheating Spinodals in $Mn_{1.85}Co_{0.15}Sb$ using Scanning Hall Probe Microscopy

TL;DR

This study visualizes the mesoscopic magnetic phase coexistence and hysteresis in Mn1.85Co0.15Sb during a first-order transition using scanning Hall probe microscopy, revealing path-dependent magnetic states at 120K.

Contribution

It provides the first mesoscopic visualization of thermomagnetic irreversibility and phase coexistence in Mn1.85Co0.15Sb across supercooling and superheating spinodals.

Findings

Hysteresis observed in magnetic states with varying field.

Magnetic state depends on the thermal path to 120K.

Mesoscopic differences in virgin and cycling states.

Abstract

Phase coexistence across disorder-broadened and magnetic-field-induced first order antiferromagnetic to ferrimagnetic transition in polycrystalline $Mn_{1.85}Co_{0.15}Sb$ has been studied mesoscopically by Scanning Hall Probe Microscope at 120K and up to 5 Tesla magnetic fields. We have observed hysteresis with varying magnetic field and the evolution of coexisting antiferromagnetic and ferrimagnetic state on mesoscopic length scale. These studies show that the magnetic state of the system at low field depends on the path followed to reach 120 K. The low field magnetic states are mesoscopically different for virgin and second field increasing cycle when 120 K is reached by warming from 5K, but are the same within measurement accuracy when the measuring temperature of 120K is reached from 300K by cooling.