Gapless Spin Wave Transport through a Quantum Canted Antiferromagnet

In the Landau levels of a two-dimensional electron system or when flat bands are present, e.g., in twisted van der Waals bilayers, strong electron-electron interaction gives rise to quantum Hall ferromagnetism with spontaneously broken symmetries in the spin and isospin sectors. Quantum Hall ferroma...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Hailong Fu, Ke Huang, Kenji Watanabe, Takashi Taniguchi, Jun Zhu
Formato:	article
Lenguaje:	EN
Publicado:	American Physical Society 2021
Materias:	Physics QC1-999
Acceso en línea:	https://doaj.org/article/5f6ca86c96b54e45a967475074a501e7
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:5f6ca86c96b54e45a967475074a501e7
record_format	dspace
spelling	oai:doaj.org-article:5f6ca86c96b54e45a967475074a501e72021-12-02T18:04:55ZGapless Spin Wave Transport through a Quantum Canted Antiferromagnet10.1103/PhysRevX.11.0210122160-3308https://doaj.org/article/5f6ca86c96b54e45a967475074a501e72021-04-01T00:00:00Zhttp://doi.org/10.1103/PhysRevX.11.021012http://doi.org/10.1103/PhysRevX.11.021012https://doaj.org/toc/2160-3308In the Landau levels of a two-dimensional electron system or when flat bands are present, e.g., in twisted van der Waals bilayers, strong electron-electron interaction gives rise to quantum Hall ferromagnetism with spontaneously broken symmetries in the spin and isospin sectors. Quantum Hall ferromagnets support a rich variety of low-energy collective excitations that are instrumental to understand the nature of the magnetic ground states and are also potentially useful as carriers of quantum information. Probing such collective excitations, especially their dispersion ω(k), is experimentally challenging due to small sample size and measurement constraints. In this work, we demonstrate an all-electrical approach that integrates a Fabry-Pérot cavity with nonequilibrium transport to achieve the excitation, wave vector selection, and detection of spin waves in graphene heterostructures. Our experiments reveal gapless, linearly dispersed spin wave excitations in the E=0 Landau level of bilayer graphene, thus providing direct experimental evidence for a predicted canted antiferromagnetic order. We show that the gapless spin wave mode propagates with a high group velocity of several tens of kilometers per second and maintains phase coherence over a distance of many micrometers. Its dependence on the magnetic field and temperature agree well with the hydrodynamic theory of spin waves. These results lay the foundation for the quest of spin superfluidity in this high-quality material. The resonant cavity technique we develop offers a powerful and timely method to explore the collective excitation of many spin- and isospin-ordered many-body ground states in van der Waals heterostructures and opens the possibility of engineering magnonic devices.Hailong FuKe HuangKenji WatanabeTakashi TaniguchiJun ZhuAmerican Physical SocietyarticlePhysicsQC1-999ENPhysical Review X, Vol 11, Iss 2, p 021012 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999
spellingShingle	Physics QC1-999 Hailong Fu Ke Huang Kenji Watanabe Takashi Taniguchi Jun Zhu Gapless Spin Wave Transport through a Quantum Canted Antiferromagnet
description	In the Landau levels of a two-dimensional electron system or when flat bands are present, e.g., in twisted van der Waals bilayers, strong electron-electron interaction gives rise to quantum Hall ferromagnetism with spontaneously broken symmetries in the spin and isospin sectors. Quantum Hall ferromagnets support a rich variety of low-energy collective excitations that are instrumental to understand the nature of the magnetic ground states and are also potentially useful as carriers of quantum information. Probing such collective excitations, especially their dispersion ω(k), is experimentally challenging due to small sample size and measurement constraints. In this work, we demonstrate an all-electrical approach that integrates a Fabry-Pérot cavity with nonequilibrium transport to achieve the excitation, wave vector selection, and detection of spin waves in graphene heterostructures. Our experiments reveal gapless, linearly dispersed spin wave excitations in the E=0 Landau level of bilayer graphene, thus providing direct experimental evidence for a predicted canted antiferromagnetic order. We show that the gapless spin wave mode propagates with a high group velocity of several tens of kilometers per second and maintains phase coherence over a distance of many micrometers. Its dependence on the magnetic field and temperature agree well with the hydrodynamic theory of spin waves. These results lay the foundation for the quest of spin superfluidity in this high-quality material. The resonant cavity technique we develop offers a powerful and timely method to explore the collective excitation of many spin- and isospin-ordered many-body ground states in van der Waals heterostructures and opens the possibility of engineering magnonic devices.
format	article
author	Hailong Fu Ke Huang Kenji Watanabe Takashi Taniguchi Jun Zhu
author_facet	Hailong Fu Ke Huang Kenji Watanabe Takashi Taniguchi Jun Zhu
author_sort	Hailong Fu
title	Gapless Spin Wave Transport through a Quantum Canted Antiferromagnet
title_short	Gapless Spin Wave Transport through a Quantum Canted Antiferromagnet
title_full	Gapless Spin Wave Transport through a Quantum Canted Antiferromagnet
title_fullStr	Gapless Spin Wave Transport through a Quantum Canted Antiferromagnet
title_full_unstemmed	Gapless Spin Wave Transport through a Quantum Canted Antiferromagnet
title_sort	gapless spin wave transport through a quantum canted antiferromagnet
publisher	American Physical Society
publishDate	2021
url	https://doaj.org/article/5f6ca86c96b54e45a967475074a501e7
work_keys_str_mv	AT hailongfu gaplessspinwavetransportthroughaquantumcantedantiferromagnet AT kehuang gaplessspinwavetransportthroughaquantumcantedantiferromagnet AT kenjiwatanabe gaplessspinwavetransportthroughaquantumcantedantiferromagnet AT takashitaniguchi gaplessspinwavetransportthroughaquantumcantedantiferromagnet AT junzhu gaplessspinwavetransportthroughaquantumcantedantiferromagnet
_version_	1718378689287159808

Gapless Spin Wave Transport through a Quantum Canted Antiferromagnet

Ejemplares similares