Excitations in the field-induced quantum spin liquid state of α-RuCl3

Arnab Banerjee; Paula Lampen-Kelley; Johannes Knolle; Christian Balz; Adam Anthony Aczel; Barry Winn; Yaohua Liu; Daniel Pajerowski; Jiaqiang Yan; Craig A. Bridges; Andrei T. Savici; Bryan C. Chakoumakos; Mark D. Lumsden; David Alan Tennant; Roderich Moessner; David G. Mandrus; Stephen E. Nagler

doi:10.1038/s41535-018-0079-2

Excitations in the field-induced quantum spin liquid state of α-RuCl₃

Arnab Banerjee, Paula Lampen-Kelley, Johannes Knolle, Christian Balz, Adam Anthony Aczel, Barry Winn, Yaohua Liu, Daniel Pajerowski, Jiaqiang Yan, Craig A. Bridges, Andrei T. Savici, Bryan C. Chakoumakos, Mark D. Lumsden, David Alan Tennant, Roderich Moessner, David G. Mandrus, Stephen E. Nagler

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Abstract

The celebrated Kitaev quantum spin liquid (QSL) is the paradigmatic example of a topological magnet with emergent excitations in the form of Majorana Fermions and gauge fluxes. Upon breaking of time-reversal symmetry, for example in an external magnetic field, these fractionalized quasiparticles acquire non-Abelian exchange statistics, an important ingredient for topologically protected quantum computing. Consequently, there has been enormous interest in exploring possible material realizations of Kitaev physics and several candidate materials have been put forward, recently including α-RuCl₃. In the absence of a magnetic field this material orders at a finite temperature and exhibits low-energy spin wave excitations. However, at moderate energies, the spectrum is unconventional and the response shows evidence for fractional excitations. Here we use time-of-flight inelastic neutron scattering to show that the application of a sufficiently large magnetic field in the honeycomb plane suppresses the magnetic order and the spin waves, leaving a gapped continuum spectrum of magnetic excitations. Our comparisons of the scattering to the available calculations for a Kitaev QSL show that they are consistent with the magnetic field induced QSL phase.

Original language	English
Article number	8
Journal	npj Quantum Materials
Volume	3
Issue number	1
DOIs	https://doi.org/10.1038/s41535-018-0079-2
State	Published - Dec 1 2018

Funding

The authors acknowledge valuable discussions with Christian Batista, Huibo Cao, Matt Stone, Feng Ye, Andrey Podelsnyak. and Matthius Vojta. J.K. and R.M. particularly thank John Chalker and Dmitri Kovrizhin for collaboration on closely related work. A. B. and P.K. thank S. Chi, O. Garlea, N. Helton, J. Werner, R. Moody and M. B. Stone for assistance with the measurement on HB-3, CORELLI and HYSPEC and G. Martin for assistance with vector-graphics. The work at ORNL’s Spallation Neutron Source and the High Flux Isotope Reactor was supported by the United States Department of Energy (US-DOE), Office of Science - Basic Energy Sciences (BES), Scientific User Facilities Division, managed by UT-Battelle LLC under contract number DEAC05-00OR22725. Part of the research was supported by the US-DOE, Office of Science - BES, Materials Sciences and Engineering Division (P.K., C.A.B. and J-Q.Y.). D.M. and P.K. acknowledge support from the Gordon and Betty Moore Foundation’s EPiQS Initiative through Grant GBMF4416. The work at Dresden was in part supported by DFG grant SFB 1143 (J.K. and R.M.). J.K. is supported by the Marie Curie Programme under EC Grant agreements No.703697.

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Banerjee, A., Lampen-Kelley, P., Knolle, J., Balz, C., Aczel, A. A., Winn, B., Liu, Y., Pajerowski, D., Yan, J., Bridges, C. A., Savici, A. T., Chakoumakos, B. C., Lumsden, M. D., Tennant, D. A., Moessner, R., Mandrus, D. G., & Nagler, S. E. (2018). Excitations in the field-induced quantum spin liquid state of α-RuCl₃ npj Quantum Materials, 3(1), Article 8. https://doi.org/10.1038/s41535-018-0079-2

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title = "Excitations in the field-induced quantum spin liquid state of α-RuCl3 ",

abstract = "The celebrated Kitaev quantum spin liquid (QSL) is the paradigmatic example of a topological magnet with emergent excitations in the form of Majorana Fermions and gauge fluxes. Upon breaking of time-reversal symmetry, for example in an external magnetic field, these fractionalized quasiparticles acquire non-Abelian exchange statistics, an important ingredient for topologically protected quantum computing. Consequently, there has been enormous interest in exploring possible material realizations of Kitaev physics and several candidate materials have been put forward, recently including α-RuCl3. In the absence of a magnetic field this material orders at a finite temperature and exhibits low-energy spin wave excitations. However, at moderate energies, the spectrum is unconventional and the response shows evidence for fractional excitations. Here we use time-of-flight inelastic neutron scattering to show that the application of a sufficiently large magnetic field in the honeycomb plane suppresses the magnetic order and the spin waves, leaving a gapped continuum spectrum of magnetic excitations. Our comparisons of the scattering to the available calculations for a Kitaev QSL show that they are consistent with the magnetic field induced QSL phase.",

author = "Arnab Banerjee and Paula Lampen-Kelley and Johannes Knolle and Christian Balz and Aczel, {Adam Anthony} and Barry Winn and Yaohua Liu and Daniel Pajerowski and Jiaqiang Yan and Bridges, {Craig A.} and Savici, {Andrei T.} and Chakoumakos, {Bryan C.} and Lumsden, {Mark D.} and Tennant, {David Alan} and Roderich Moessner and Mandrus, {David G.} and Nagler, {Stephen E.}",

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year = "2018",

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doi = "10.1038/s41535-018-0079-2",

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Banerjee, A, Lampen-Kelley, P, Knolle, J, Balz, C , Aczel, AA , Winn, B , Liu, Y , Pajerowski, D , Yan, J , Bridges, CA , Savici, AT, Chakoumakos, BC, Lumsden, MD, Tennant, DA, Moessner, R, Mandrus, DG & Nagler, SE 2018, 'Excitations in the field-induced quantum spin liquid state of α-RuCl₃ ', npj Quantum Materials, vol. 3, no. 1, 8. https://doi.org/10.1038/s41535-018-0079-2

TY - JOUR

T1 - Excitations in the field-induced quantum spin liquid state of α-RuCl3

AU - Banerjee, Arnab

AU - Lampen-Kelley, Paula

AU - Knolle, Johannes

AU - Balz, Christian

AU - Aczel, Adam Anthony

AU - Winn, Barry

AU - Liu, Yaohua

AU - Pajerowski, Daniel

AU - Yan, Jiaqiang

AU - Bridges, Craig A.

AU - Savici, Andrei T.

AU - Chakoumakos, Bryan C.

AU - Lumsden, Mark D.

AU - Tennant, David Alan

AU - Moessner, Roderich

AU - Mandrus, David G.

AU - Nagler, Stephen E.

PY - 2018/12/1

Y1 - 2018/12/1

N2 - The celebrated Kitaev quantum spin liquid (QSL) is the paradigmatic example of a topological magnet with emergent excitations in the form of Majorana Fermions and gauge fluxes. Upon breaking of time-reversal symmetry, for example in an external magnetic field, these fractionalized quasiparticles acquire non-Abelian exchange statistics, an important ingredient for topologically protected quantum computing. Consequently, there has been enormous interest in exploring possible material realizations of Kitaev physics and several candidate materials have been put forward, recently including α-RuCl3. In the absence of a magnetic field this material orders at a finite temperature and exhibits low-energy spin wave excitations. However, at moderate energies, the spectrum is unconventional and the response shows evidence for fractional excitations. Here we use time-of-flight inelastic neutron scattering to show that the application of a sufficiently large magnetic field in the honeycomb plane suppresses the magnetic order and the spin waves, leaving a gapped continuum spectrum of magnetic excitations. Our comparisons of the scattering to the available calculations for a Kitaev QSL show that they are consistent with the magnetic field induced QSL phase.

AB - The celebrated Kitaev quantum spin liquid (QSL) is the paradigmatic example of a topological magnet with emergent excitations in the form of Majorana Fermions and gauge fluxes. Upon breaking of time-reversal symmetry, for example in an external magnetic field, these fractionalized quasiparticles acquire non-Abelian exchange statistics, an important ingredient for topologically protected quantum computing. Consequently, there has been enormous interest in exploring possible material realizations of Kitaev physics and several candidate materials have been put forward, recently including α-RuCl3. In the absence of a magnetic field this material orders at a finite temperature and exhibits low-energy spin wave excitations. However, at moderate energies, the spectrum is unconventional and the response shows evidence for fractional excitations. Here we use time-of-flight inelastic neutron scattering to show that the application of a sufficiently large magnetic field in the honeycomb plane suppresses the magnetic order and the spin waves, leaving a gapped continuum spectrum of magnetic excitations. Our comparisons of the scattering to the available calculations for a Kitaev QSL show that they are consistent with the magnetic field induced QSL phase.

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JO - npj Quantum Materials

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ER -

Excitations in the field-induced quantum spin liquid state of α-RuCl₃

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