Skip to main content
U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Https

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Site-Specific Structure at Multiple Length Scales in Kagome Quantum Spin Liquid Candidates

Published

Author(s)

Rebecca W. Smaha, Idris Boukahil, Charles J. Titus, Jack Mingde Jiang, John P. Sheckelton, Wei He, JiaJia Wen, John T. Vinson, SuYin G. Wang, Yu-Sheng Chen, Simon J. Teat, Thomas P. Devereaux, Chaitanya D. Pemmaraju, Young S. Lee

Abstract

Realizing a quantum spin liquid (QSL) ground state in a real material is a leading issue in condensed matter physics research. In this pursuit, it is crucial to fully characterize the structure and influence of defects, as these can significantly affect the fragile QSL physics. Here, we perform a variety of cutting-edge synchrotron X-ray scattering and spectroscopy techniques, and we advance new methodologies for site-specific diffraction and L-edge Zn absorption spectroscopy. The experimental results along with our first- principles calculations address outstanding questions about the local and long-range structures of the two leading kagome QSL candidates, Zn-substituted bar- lowite (Cu3ZnxCu1−x(OH)6FBr) and herbertsmithite (Cu3Zn0.85Cu0.15(OH)6Cl2). On all length scales probed, there is no evidence that Zn substitutes onto the kagome layers, thereby preserving the QSL physics of the kagome lattice. Our calculations show that antisite disorder is not energetically favorable and is even less favorable in Zn-barlowite compared to herbertsmithite. Site-specific X-ray diffraction measurements of Zn-barlowite reveal that Cu2+ and Zn2+ selectively occupy dis- tinct interlayer sites, in contrast to herbertsmithite. Using the first measured Zn L-edge inelastic X- ray absorption spectra combined with calculations, we discover a systematic correlation between the loss of inversion symmetry from pseudo-octahedral (herbertsmithite) to trigonal prismatic coordination (Zn-barlowite) with the emergence of a new peak. Overall, our measurements suggest that Zn-barlowite has structural advantages over herbertsmithite for being an ideal QSL candidate: its kagome layers are highly resistant to nonmagnetic defects while the interlayers can accommodate a higher amount of Zn substitution.
Citation
Physical Review Materials
Volume
4
Created December 13, 2020, Updated December 14, 2020