All-in-all-out magnetic domain size in pyrochlore iridate thin films as probed by local magnetotransport

TL;DR

This study uses local magnetotransport measurements to estimate the size of magnetic domains in Eu2Ir2O7 thin films, revealing domain sizes of 1-2 micrometers and their distribution depending on cooling conditions.

Contribution

It introduces a magnetotransport method to directly estimate magnetic domain sizes in pyrochlore iridate thin films, linking domain size to linear magnetoresistance behavior.

Findings

Magnetic domains are estimated to be 1-2 μm in size.

Domain distribution varies with cooling cycle and channel size.

Linear MR sign indicates different domain ratios in the sample.

Abstract

Pyrochlore iridates have attracted growing attention because of a theoretical prediction of a possible topological semimetal phase originating from all-in-all-out spin ordering. Related to the topological band structure, recent findings of the magnetic domain wall conduction have stimulated investigations of magnetic domain distribution in this system. Here, we investigate the size of magnetic domains in Eu$_2$Ir$_2$O$_7$ single crystalline thin films by magnetoresistance (MR) using microscale Hall bars. Two distinct magnetic domains of the all-in-all-out spin structure are known to exhibit linear MR but with opposite signs, which enables us to estimate the ratio of the two domains in the patterned channel. The linear MR for 80 ${\times}$ 60 ${\mu}$m$^2$ channel is nearly zero after zero-field cooling, suggesting random distribution of domains smaller than the channel size. In contrast, the wide distribution of the value of the linear MR is detected in 2 ${\times}$ 2 ${\mu}$m$^2$ channel, reflecting the detectable domain size depending on each cooling-cycle. Compared to simulation results, we estimate the average size of a single all-in-all-out magnetic domain as 1-2 ${\mu}$m.