Broadband Terahertz Probes of Anisotropic Magnetoresistance Disentangle Extrinsic and Intrinsic Contributions

Anisotropic magnetoresistance (AMR) is a ubiquitous and versatile probe of magnetic order in contemporary spintronics research. Its origins are usually ascribed to extrinsic effects (i.e., spin-dependent electron scattering), whereas intrinsic (i.e., scattering-independent) contributions are neglect...

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Autores principales:	Lukáš Nádvorník, Martin Borchert, Liane Brandt, Richard Schlitz, Koen A. de Mare, Karel Výborný, Ingrid Mertig, Gerhard Jakob, Matthias Kläui, Sebastian T. B. Goennenwein, Martin Wolf, Georg Woltersdorf, Tobias Kampfrath
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Lenguaje:	EN
Publicado:	American Physical Society 2021
Materias:	Physics QC1-999
Acceso en línea:	https://doaj.org/article/abb7c42fed2f45e189c625e22ffde123
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spelling	oai:doaj.org-article:abb7c42fed2f45e189c625e22ffde1232021-12-02T15:36:48ZBroadband Terahertz Probes of Anisotropic Magnetoresistance Disentangle Extrinsic and Intrinsic Contributions10.1103/PhysRevX.11.0210302160-3308https://doaj.org/article/abb7c42fed2f45e189c625e22ffde1232021-05-01T00:00:00Zhttp://doi.org/10.1103/PhysRevX.11.021030http://doi.org/10.1103/PhysRevX.11.021030https://doaj.org/toc/2160-3308Anisotropic magnetoresistance (AMR) is a ubiquitous and versatile probe of magnetic order in contemporary spintronics research. Its origins are usually ascribed to extrinsic effects (i.e., spin-dependent electron scattering), whereas intrinsic (i.e., scattering-independent) contributions are neglected. Here, we measure AMR of polycrystalline thin films of the standard ferromagnets Co, Ni, Ni_{81}Fe_{19}, and Ni_{50}Fe_{50} over the frequency range from dc to 28 THz. The large bandwidth covers the regimes of both diffusive and ballistic intraband electron transport and, thus, allows us to separate extrinsic and intrinsic AMR components. Analysis of the THz response based on Boltzmann transport theory reveals that the AMR of the Ni, Ni_{81}Fe_{19}, and Ni_{50}Fe_{50} samples is of predominantly extrinsic nature. However, the Co thin film exhibits a sizable intrinsic AMR contribution, which is constant up to 28 THz and amounts to more than 2/3 of the dc AMR contrast of 1%. These features are attributed to the hexagonal structure of the Co crystallites. They are interesting for applications in terahertz spintronics and terahertz photonics. Our results show that broadband terahertz electromagnetic pulses provide new and contact-free insights into magnetotransport phenomena of standard magnetic thin films on ultrafast timescales.Lukáš NádvorníkMartin BorchertLiane BrandtRichard SchlitzKoen A. de MareKarel VýbornýIngrid MertigGerhard JakobMatthias KläuiSebastian T. B. GoennenweinMartin WolfGeorg WoltersdorfTobias KampfrathAmerican Physical SocietyarticlePhysicsQC1-999ENPhysical Review X, Vol 11, Iss 2, p 021030 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999
spellingShingle	Physics QC1-999 Lukáš Nádvorník Martin Borchert Liane Brandt Richard Schlitz Koen A. de Mare Karel Výborný Ingrid Mertig Gerhard Jakob Matthias Kläui Sebastian T. B. Goennenwein Martin Wolf Georg Woltersdorf Tobias Kampfrath Broadband Terahertz Probes of Anisotropic Magnetoresistance Disentangle Extrinsic and Intrinsic Contributions
description	Anisotropic magnetoresistance (AMR) is a ubiquitous and versatile probe of magnetic order in contemporary spintronics research. Its origins are usually ascribed to extrinsic effects (i.e., spin-dependent electron scattering), whereas intrinsic (i.e., scattering-independent) contributions are neglected. Here, we measure AMR of polycrystalline thin films of the standard ferromagnets Co, Ni, Ni_{81}Fe_{19}, and Ni_{50}Fe_{50} over the frequency range from dc to 28 THz. The large bandwidth covers the regimes of both diffusive and ballistic intraband electron transport and, thus, allows us to separate extrinsic and intrinsic AMR components. Analysis of the THz response based on Boltzmann transport theory reveals that the AMR of the Ni, Ni_{81}Fe_{19}, and Ni_{50}Fe_{50} samples is of predominantly extrinsic nature. However, the Co thin film exhibits a sizable intrinsic AMR contribution, which is constant up to 28 THz and amounts to more than 2/3 of the dc AMR contrast of 1%. These features are attributed to the hexagonal structure of the Co crystallites. They are interesting for applications in terahertz spintronics and terahertz photonics. Our results show that broadband terahertz electromagnetic pulses provide new and contact-free insights into magnetotransport phenomena of standard magnetic thin films on ultrafast timescales.
format	article
author	Lukáš Nádvorník Martin Borchert Liane Brandt Richard Schlitz Koen A. de Mare Karel Výborný Ingrid Mertig Gerhard Jakob Matthias Kläui Sebastian T. B. Goennenwein Martin Wolf Georg Woltersdorf Tobias Kampfrath
author_facet	Lukáš Nádvorník Martin Borchert Liane Brandt Richard Schlitz Koen A. de Mare Karel Výborný Ingrid Mertig Gerhard Jakob Matthias Kläui Sebastian T. B. Goennenwein Martin Wolf Georg Woltersdorf Tobias Kampfrath
author_sort	Lukáš Nádvorník
title	Broadband Terahertz Probes of Anisotropic Magnetoresistance Disentangle Extrinsic and Intrinsic Contributions
title_short	Broadband Terahertz Probes of Anisotropic Magnetoresistance Disentangle Extrinsic and Intrinsic Contributions
title_full	Broadband Terahertz Probes of Anisotropic Magnetoresistance Disentangle Extrinsic and Intrinsic Contributions
title_fullStr	Broadband Terahertz Probes of Anisotropic Magnetoresistance Disentangle Extrinsic and Intrinsic Contributions
title_full_unstemmed	Broadband Terahertz Probes of Anisotropic Magnetoresistance Disentangle Extrinsic and Intrinsic Contributions
title_sort	broadband terahertz probes of anisotropic magnetoresistance disentangle extrinsic and intrinsic contributions
publisher	American Physical Society
publishDate	2021
url	https://doaj.org/article/abb7c42fed2f45e189c625e22ffde123
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Broadband Terahertz Probes of Anisotropic Magnetoresistance Disentangle Extrinsic and Intrinsic Contributions

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