Asymmetric Magnetic Relaxation Behavior of Domains and Domain Walls Observed Through the FeRh First-Order Metamagnetic Phase Transition

The phase coexistence present through a first-order phase transition meansthere will be finite regions between the two phases where the structure of thesystem will vary from one phase to the other, known as a phase boundary wall.This region is said to play an important but unknown role in the dynamics ofthe first-order phase transitions. Here, by using both x-ray photon correlationspectroscopy and magnetometry techniques to measure the temporal isothermaldevelopment at various points through the thermally activated first-ordermetamagnetic phase transition present in the near-equiatomic FeRh alloy, we areable to isolate the dynamic behavior of the domain walls in this system. Theseinvestigations reveal that relaxation behavior of the domain walls changes whenphase coexistence is introduced into the system and that the domain walldynamics is different to the macroscale behavior. We attribute this to theeffect of the exchange coupling between regions of either magnetic phasechanging the dynamic properties of domain walls relative to bulk regions ofeither phase. We also believe this behavior comes from the influence of thephase boundary wall on other magnetic objects in the system.