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Title: Field evolution of magnons in α - RuCl 3 by high-resolution polarized terahertz spectroscopy

Abstract

The Kitaev quantum spin liquid (KSL) is a theoretically predicted state of matter whose fractionalized quasiparticles are distinct from bosonic magnons, the fundamental excitation in ordered magnets. The layered honeycomb antiferromagnet α-RuCl3 is a KSL candidate material, as it can be driven to a magnetically disordered phase by application of an in-plane magnetic field, with Hc~7T. Here, we report a detailed characterization of the magnetic excitation spectrum of this material by high-resolution time-domain terahertz spectroscopy. We observe two sharp magnon resonances whose frequencies and amplitudes exhibit a discontinuity as a function of applied magnetic field, as well as two broader peaks at higher energy. Below the Néel temperature, we find that linear spin wave theory can account for all of these essential features of the spectra when a C3-breaking distortion of the honeycomb lattice and the presence of structural domains are taken into account.

Authors:
 [1];  [2];  [3];  [2];  [2];  [4];  [5];  [5];  [5];  [6];  [2];  [6];  [4];  [5];  [3];  [2]
  1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of Pennsylvania, Philadelphia, PA (United States)
  2. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Univ. of California, Berkeley, CA (United States)
  4. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  6. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; Gordon and Betty Moore Foundation; USDOE
OSTI Identifier:
1562881
Alternate Identifier(s):
OSTI ID: 1474001; OSTI ID: 1761765
Grant/Contract Number:  
KC2206; AC02-05-CH11231; AC02-05CH11231; AC02-76SF00515; AC05-00OR22725; GBMF4537
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 98; Journal Issue: 9; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Wu, Liang, Little, A., Aldape, E. E., Rees, D., Thewalt, E., Lampen-Kelley, P., Banerjee, A., Bridges, C. A., Yan, J. -Q., Boone, D., Patankar, S., Goldhaber-Gordon, D., Mandrus, D., Nagler, S. E., Altman, E., and Orenstein, J. Field evolution of magnons in α-RuCl3 by high-resolution polarized terahertz spectroscopy. United States: N. p., 2018. Web. https://doi.org/10.1103/physrevb.98.094425.
Wu, Liang, Little, A., Aldape, E. E., Rees, D., Thewalt, E., Lampen-Kelley, P., Banerjee, A., Bridges, C. A., Yan, J. -Q., Boone, D., Patankar, S., Goldhaber-Gordon, D., Mandrus, D., Nagler, S. E., Altman, E., & Orenstein, J. Field evolution of magnons in α-RuCl3 by high-resolution polarized terahertz spectroscopy. United States. https://doi.org/10.1103/physrevb.98.094425
Wu, Liang, Little, A., Aldape, E. E., Rees, D., Thewalt, E., Lampen-Kelley, P., Banerjee, A., Bridges, C. A., Yan, J. -Q., Boone, D., Patankar, S., Goldhaber-Gordon, D., Mandrus, D., Nagler, S. E., Altman, E., and Orenstein, J. Wed . "Field evolution of magnons in α-RuCl3 by high-resolution polarized terahertz spectroscopy". United States. https://doi.org/10.1103/physrevb.98.094425. https://www.osti.gov/servlets/purl/1562881.
@article{osti_1562881,
title = {Field evolution of magnons in α-RuCl3 by high-resolution polarized terahertz spectroscopy},
author = {Wu, Liang and Little, A. and Aldape, E. E. and Rees, D. and Thewalt, E. and Lampen-Kelley, P. and Banerjee, A. and Bridges, C. A. and Yan, J. -Q. and Boone, D. and Patankar, S. and Goldhaber-Gordon, D. and Mandrus, D. and Nagler, S. E. and Altman, E. and Orenstein, J.},
abstractNote = {The Kitaev quantum spin liquid (KSL) is a theoretically predicted state of matter whose fractionalized quasiparticles are distinct from bosonic magnons, the fundamental excitation in ordered magnets. The layered honeycomb antiferromagnet α-RuCl3 is a KSL candidate material, as it can be driven to a magnetically disordered phase by application of an in-plane magnetic field, with Hc~7T. Here, we report a detailed characterization of the magnetic excitation spectrum of this material by high-resolution time-domain terahertz spectroscopy. We observe two sharp magnon resonances whose frequencies and amplitudes exhibit a discontinuity as a function of applied magnetic field, as well as two broader peaks at higher energy. Below the Néel temperature, we find that linear spin wave theory can account for all of these essential features of the spectra when a C3-breaking distortion of the honeycomb lattice and the presence of structural domains are taken into account.},
doi = {10.1103/physrevb.98.094425},
journal = {Physical Review B},
number = 9,
volume = 98,
place = {United States},
year = {2018},
month = {9}
}

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Cited by: 7 works
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Figures / Tables:

Fig. 1 Fig. 1: (a) Transmitted THz electric eld amplitude at T = 294 K as a function of sample angle. Blue and red lines represent the minimum transmission axes at a' and b' (b) Schematic of honeycomb structure showing a and b monoclinic axes relative to Ru-Ru bonds. Color of atomsmore » illustrates zigzag order. Bond labels x, y, and z denote the component of the spin interacting along a given bond in the Kitaev model. (c) Magnon absorption as a function of frequency for Hb'BTHz and Hb'BTHz respectively. The magnon contribution is extracted from the total THz absorption by subtracting a reference at T = 8 K, above TN, from a T = 4 K spectrum at each eld. Traces are o set for clarity.« less

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