Homotopy-Theoretic Study &Atomic-Scale Observation of Vortex Domains in Hexagonal Manganites

Jun Li; Fu-Kuo Chiang; Zhen Chen; Chao Ma; Ming-Wen Chu; Cheng-Hsuan Chen; Huanfang Tian; Huaixin Yang; Jianqi Li

doi:10.1038/srep28047

Homotopy-Theoretic Study &Atomic-Scale Observation of Vortex Domains in Hexagonal Manganites

Sci Rep. 2016 Jun 21:6:28047. doi: 10.1038/srep28047.

Authors

Jun Li^{1

2}, Fu-Kuo Chiang^{1

3}, Zhen Chen^{1

2}, Chao Ma¹, Ming-Wen Chu⁴, Cheng-Hsuan Chen^{4

5}, Huanfang Tian¹, Huaixin Yang^{1

2}, Jianqi Li^{1

2

6}

Affiliations

¹ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.
³ National Institute of Clean-and-Low-Carbon Energy, Beijing 100209, China.
⁴ Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan.
⁵ Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
⁶ Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China.

Abstract

Essential structural properties of the non-trivial "string-wall-bounded" topological defects in hexagonal manganites are studied through homotopy group theory and spherical aberration-corrected scanning transmission electron microscopy. The appearance of a "string-wall-bounded" configuration in RMnO3 is shown to be strongly linked with the transformation of the degeneracy space. The defect core regions (~50 Å) mainly adopt the continuous U(1) symmetry of the high-temperature phase, which is essential for the formation and proliferation of vortices. Direct visualization of vortex strings at atomic scale provides insight into the mechanisms and macro-behavior of topological defects in crystalline materials.

Publication types

Research Support, Non-U.S. Gov't