Thermodynamics of free and bound magnons in graphene
Abstract
Symmetry-broken electronic phases support neutral collective excitations. For example, monolayer graphene in the quantum Hall regime hosts a nearly ideal ferromagnetic phase at specific filling factors that spontaneously breaks the spin-rotation symmetry. This ferromagnet has been shown to support spin-wave excitations known as magnons that can be electrically generated and detected. Although long-distance magnon propagation has been demonstrated via transport measurements, important thermodynamic properties of such magnon populations—including the magnon chemical potential and density—have not been measured. Here we present local measurements of electron compressibility under the influence of magnons, which reveal a reduction in the gap associated with the ν = 1 quantum Hall state by up to 20%. Combining these measurements with the estimates of temperature, our analysis reveals that the injected magnons bind to electrons and holes to form skyrmions, and it enables the extraction of free magnon density, magnon chemical potential and average skyrmion spin. Our methods provide a means of probing the thermodynamic properties of charge-neutral excitations that are applicable to other symmetry-broken electronic phases.
- Authors:
-
[2];
[1];
[3];
[3];
[1];
[1]
- Harvard University, Cambridge, MA (United States)
- Harvard University, Cambridge, MA (United States); Massachusetts Institute of Technology (MIT), Cambridge, MA (United States)
- National Institute for Materials Science, Tsukuba (Japan)
- Publication Date:
- Research Org.:
- Harvard Univ., Cambridge, MA (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE); Gordon and Betty Moore Foundation; Army Research Office (ARO); National Science Foundation (NSF); Department of Defense (DoD); Harvard Quantum Initiative in Science and Engineering; Harvard Quantum Initiative Seed Fund; Japan Society for the Promotion of Science (JSPS)
- OSTI Identifier:
- 1978663
- Grant/Contract Number:
- SC0001819; SC0019300; GBMF9468; W911NF-14-1-0247; DMR-1231319; DGE 1745303; JPMXP0112101001; JP20H00354; ECS-0335765
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Nature Physics
- Additional Journal Information:
- Journal Volume: 18; Journal Issue: 1; Journal ID: ISSN 1745-2473
- Publisher:
- Nature Publishing Group (NPG)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; electronics properties; electronic devices; quantum hall; spintronics; thermodynamics
Citation Formats
Pierce, Andrew T., Xie, Yonglong, Lee, Seung Hwan, Forrester, Patrick R., Wei, Di S., Watanabe, Kenji, Taniguchi, Takashi, Halperin, Bertrand I., and Yacoby, Amir. Thermodynamics of free and bound magnons in graphene. United States: N. p., 2021.
Web. doi:10.1038/s41567-021-01421-x.
Pierce, Andrew T., Xie, Yonglong, Lee, Seung Hwan, Forrester, Patrick R., Wei, Di S., Watanabe, Kenji, Taniguchi, Takashi, Halperin, Bertrand I., & Yacoby, Amir. Thermodynamics of free and bound magnons in graphene. United States. https://doi.org/10.1038/s41567-021-01421-x
Pierce, Andrew T., Xie, Yonglong, Lee, Seung Hwan, Forrester, Patrick R., Wei, Di S., Watanabe, Kenji, Taniguchi, Takashi, Halperin, Bertrand I., and Yacoby, Amir. Mon .
"Thermodynamics of free and bound magnons in graphene". United States. https://doi.org/10.1038/s41567-021-01421-x. https://www.osti.gov/servlets/purl/1978663.
@article{osti_1978663,
title = {Thermodynamics of free and bound magnons in graphene},
author = {Pierce, Andrew T. and Xie, Yonglong and Lee, Seung Hwan and Forrester, Patrick R. and Wei, Di S. and Watanabe, Kenji and Taniguchi, Takashi and Halperin, Bertrand I. and Yacoby, Amir},
abstractNote = {Symmetry-broken electronic phases support neutral collective excitations. For example, monolayer graphene in the quantum Hall regime hosts a nearly ideal ferromagnetic phase at specific filling factors that spontaneously breaks the spin-rotation symmetry. This ferromagnet has been shown to support spin-wave excitations known as magnons that can be electrically generated and detected. Although long-distance magnon propagation has been demonstrated via transport measurements, important thermodynamic properties of such magnon populations—including the magnon chemical potential and density—have not been measured. Here we present local measurements of electron compressibility under the influence of magnons, which reveal a reduction in the gap associated with the ν = 1 quantum Hall state by up to 20%. Combining these measurements with the estimates of temperature, our analysis reveals that the injected magnons bind to electrons and holes to form skyrmions, and it enables the extraction of free magnon density, magnon chemical potential and average skyrmion spin. Our methods provide a means of probing the thermodynamic properties of charge-neutral excitations that are applicable to other symmetry-broken electronic phases.},
doi = {10.1038/s41567-021-01421-x},
journal = {Nature Physics},
number = 1,
volume = 18,
place = {United States},
year = {Mon Dec 13 00:00:00 EST 2021},
month = {Mon Dec 13 00:00:00 EST 2021}
}
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