Incommensurate magnetic order in an axion insulator candidate EuIn$_2$As$_2$ investigated by NMR measurement

Fuente: arXiv
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Main Authors: Takeda, Hikaru, Yan, Jian, Jiang, Zhongzhu, Luo, Xuan, Sun, Yuping, Yamashita, Minoru
Format: Preprint
Published: 2024
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author Takeda, Hikaru
Yan, Jian
Jiang, Zhongzhu
Luo, Xuan
Sun, Yuping
Yamashita, Minoru
author_facet Takeda, Hikaru
Yan, Jian
Jiang, Zhongzhu
Luo, Xuan
Sun, Yuping
Yamashita, Minoru
contents Magnetic topological insulators exhibit unique electronic states due to the interplay between the electronic topology and the spin structure. The antiferromagnetic metal $\rm{EuIn_2As_2}$ is a prominent candidate material in which exotic topological phases, including an axion insulating state, are theoretically predicted depending on the magnetic structure of the $\rm{Eu}^{2+}$ moments. Here, we report experimental results of the nuclear magnetic resonance (NMR) measurements of all the nuclei in $\rm{EuIn_2As_2}$ to investigate the coupling between the magnetic moments in the Eu ions and the conduction electrons in $\rm{In_2As_2}$ layers and the magnetic structure. The $^{75}\rm{As}$ and $^{115}\rm{In}$ NMR spectra observed at zero external magnetic field reveal the appearance of internal fields of $4.9$ and $3.6\ \rm{T}$ respectively at the lowest temperature, suggesting a strong coupling between the conduction electrons in the $\rm{In_2As_2}$ layer and the ordered magnetic moments in the Eu ions. The $^{75}\rm{As}$ NMR spectra under in-plane external magnetic fields show broad distributions of the internal fields produced by an incommensurate fan-like spin structure which turns into a forced ferromagnetic state above $0.7\ \rm{T}$. We propose a spin reorientation process that an incommensurate helical state at zero external magnetic field quickly changes into a fan state by applying a slight magnetic field.
format Preprint
id arxiv_https___arxiv_org_abs_2409_13211
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Incommensurate magnetic order in an axion insulator candidate EuIn$_2$As$_2$ investigated by NMR measurement
Takeda, Hikaru
Yan, Jian
Jiang, Zhongzhu
Luo, Xuan
Sun, Yuping
Yamashita, Minoru
Strongly Correlated Electrons
Magnetic topological insulators exhibit unique electronic states due to the interplay between the electronic topology and the spin structure. The antiferromagnetic metal $\rm{EuIn_2As_2}$ is a prominent candidate material in which exotic topological phases, including an axion insulating state, are theoretically predicted depending on the magnetic structure of the $\rm{Eu}^{2+}$ moments. Here, we report experimental results of the nuclear magnetic resonance (NMR) measurements of all the nuclei in $\rm{EuIn_2As_2}$ to investigate the coupling between the magnetic moments in the Eu ions and the conduction electrons in $\rm{In_2As_2}$ layers and the magnetic structure. The $^{75}\rm{As}$ and $^{115}\rm{In}$ NMR spectra observed at zero external magnetic field reveal the appearance of internal fields of $4.9$ and $3.6\ \rm{T}$ respectively at the lowest temperature, suggesting a strong coupling between the conduction electrons in the $\rm{In_2As_2}$ layer and the ordered magnetic moments in the Eu ions. The $^{75}\rm{As}$ NMR spectra under in-plane external magnetic fields show broad distributions of the internal fields produced by an incommensurate fan-like spin structure which turns into a forced ferromagnetic state above $0.7\ \rm{T}$. We propose a spin reorientation process that an incommensurate helical state at zero external magnetic field quickly changes into a fan state by applying a slight magnetic field.
title Incommensurate magnetic order in an axion insulator candidate EuIn$_2$As$_2$ investigated by NMR measurement
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2409.13211