Surface reconstruction and orthogonal decoupling in SrAl4 and EuAl4

Fuente: arXiv
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Main Authors: Li, Tongrui, Chen, Leiyuan, Yuan, Jian, Liu, Zhengtai, Yang, Yichen, Jiang, Zhicheng, Ding, Jianyang, Liu, Jiayu, Liu, Jishan, Sun, Zhe, Guo, Yanfeng, Zhang, Tong, Shen, Dawei
Format: Preprint
Published: 2025
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author Li, Tongrui
Chen, Leiyuan
Yuan, Jian
Liu, Zhengtai
Yang, Yichen
Jiang, Zhicheng
Ding, Jianyang
Liu, Jiayu
Liu, Jishan
Sun, Zhe
Guo, Yanfeng
Zhang, Tong
Shen, Dawei
author_facet Li, Tongrui
Chen, Leiyuan
Yuan, Jian
Liu, Zhengtai
Yang, Yichen
Jiang, Zhicheng
Ding, Jianyang
Liu, Jiayu
Liu, Jishan
Sun, Zhe
Guo, Yanfeng
Zhang, Tong
Shen, Dawei
contents Surface-induced symmetry breaking in quantum materials can stabilize exotic electronic phases distinct from those in the bulk, yet its momentum-space manifestations remain elusive due to domain-averaging effects. Here, using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM), we present a microscopic investigation of the electronic structures of SrAl4 and EuAl4, layered tetragonal intermetallic compounds that exhibit well-characterized incommensurate charge-density-wave (CDW) transitions. Below the CDW transition temperatures, we uncover linearly dispersing electronic states and pronounced unidirectional replica bands orthogonal to the bulk CDW wave vector, evidencing the emergence of an in-plane C4 symmetry-breaking electronic order that is not dictated by the bulk incommensurate CDW. STM measurements further reveal a 1 times 2 surface reconstruction with quasi-one-dimensional modulations and half-unit-cell steps, traced to ordered 50 percent Sr/Eu vacancies, which vanish irreversibly upon thermal cycling, indicating decoupled surface and bulk orders. These findings establish SrAl4 and EuAl4 as model platforms for exploring surface-confined nematicity and emergent low-dimensional phases in quantum materials.
format Preprint
id arxiv_https___arxiv_org_abs_2509_04742
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Surface reconstruction and orthogonal decoupling in SrAl4 and EuAl4
Li, Tongrui
Chen, Leiyuan
Yuan, Jian
Liu, Zhengtai
Yang, Yichen
Jiang, Zhicheng
Ding, Jianyang
Liu, Jiayu
Liu, Jishan
Sun, Zhe
Guo, Yanfeng
Zhang, Tong
Shen, Dawei
Materials Science
Surface-induced symmetry breaking in quantum materials can stabilize exotic electronic phases distinct from those in the bulk, yet its momentum-space manifestations remain elusive due to domain-averaging effects. Here, using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM), we present a microscopic investigation of the electronic structures of SrAl4 and EuAl4, layered tetragonal intermetallic compounds that exhibit well-characterized incommensurate charge-density-wave (CDW) transitions. Below the CDW transition temperatures, we uncover linearly dispersing electronic states and pronounced unidirectional replica bands orthogonal to the bulk CDW wave vector, evidencing the emergence of an in-plane C4 symmetry-breaking electronic order that is not dictated by the bulk incommensurate CDW. STM measurements further reveal a 1 times 2 surface reconstruction with quasi-one-dimensional modulations and half-unit-cell steps, traced to ordered 50 percent Sr/Eu vacancies, which vanish irreversibly upon thermal cycling, indicating decoupled surface and bulk orders. These findings establish SrAl4 and EuAl4 as model platforms for exploring surface-confined nematicity and emergent low-dimensional phases in quantum materials.
title Surface reconstruction and orthogonal decoupling in SrAl4 and EuAl4
topic Materials Science
url https://arxiv.org/abs/2509.04742