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THz emission from Co/Pt bilayers with varied roughness, crystal structure, and interface intermixing

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THz emission from Co/Pt bilayers with varied roughness, crystal structure, and interface intermixing. / Li, G.; Medapalli, R.; Mikhaylovskiy, R.V.; Spada, F.E.; Rasing, T.; Fullerton, E.E.; Kimel, A.V.

In: Physical Review Materials, Vol. 3, No. 8, 084415, 19.08.2019.

Research output: Contribution to journalJournal article

Harvard

Li, G, Medapalli, R, Mikhaylovskiy, RV, Spada, FE, Rasing, T, Fullerton, EE & Kimel, AV 2019, 'THz emission from Co/Pt bilayers with varied roughness, crystal structure, and interface intermixing', Physical Review Materials, vol. 3, no. 8, 084415. https://doi.org/10.1103/PhysRevMaterials.3.084415

APA

Li, G., Medapalli, R., Mikhaylovskiy, R. V., Spada, F. E., Rasing, T., Fullerton, E. E., & Kimel, A. V. (2019). THz emission from Co/Pt bilayers with varied roughness, crystal structure, and interface intermixing. Physical Review Materials, 3(8), [084415]. https://doi.org/10.1103/PhysRevMaterials.3.084415

Vancouver

Li G, Medapalli R, Mikhaylovskiy RV, Spada FE, Rasing T, Fullerton EE et al. THz emission from Co/Pt bilayers with varied roughness, crystal structure, and interface intermixing. Physical Review Materials. 2019 Aug 19;3(8). 084415. https://doi.org/10.1103/PhysRevMaterials.3.084415

Author

Li, G. ; Medapalli, R. ; Mikhaylovskiy, R.V. ; Spada, F.E. ; Rasing, T. ; Fullerton, E.E. ; Kimel, A.V. / THz emission from Co/Pt bilayers with varied roughness, crystal structure, and interface intermixing. In: Physical Review Materials. 2019 ; Vol. 3, No. 8.

Bibtex

@article{d5090f7bf4b9456aab2eee5689e88fdb,
title = "THz emission from Co/Pt bilayers with varied roughness, crystal structure, and interface intermixing",
abstract = "Ultrafast demagnetization of Co/Pt heterostructures induced by a femtosecond 800-nm laser pulse launches a spin current from Co to Pt and subsequent conversion of the spin current to a charge current in the Pt layer due to the inverse spin-Hall effect. At the same time, due to the spin-dependent photogalvanic effect, a circularly polarized femtosecond laser pulse also generates a photocurrent at the Co/Pt interface. Both ultrashort photocurrent pulses are effectively detected in a contactless way by measuring the THz radiation they emit. Here we aim to understand how the properties of the Co/Pt interface affect the photocurrents in the bilayers. By varying the interfacial roughness, crystal structure, and interfacial intermixing, as well as having an explicit focus on the cases when THz emissions from these two photocurrents reveal opposite trends, we identify which interface properties play a crucial role for the photocurrents. In particular, we show that by reducing the roughness, the THz emission due to the spin-dependent photogalvanic effect reduces to zero while the strength of the THz emission from the photocurrent associated with the inverse spin-Hall effect increases by a factor of 2. On the other hand, while intermixing strongly enhances the THz emission from the inverse spin-Hall effect by a factor of 4.2, THz emission related to the spin-dependent photogalvanic effect reveals the opposite trend. These findings indicate that microstructural properties of the Co-Pt interface play a decisive role in the generation of photocurrents. ",
keywords = "Binary alloys, Cobalt alloys, Crystal symmetry, Laser pulses, Mixing, Photocurrents, Platinum, Platinum alloys, Terahertz waves, Circularly polarized, Interface intermixing, Interface property, Interfacial intermixing, Interfacial roughness, Micro-structural properties, Photogalvanic effects, Ultrafast demagnetization, Spin Hall effect",
author = "G. Li and R. Medapalli and R.V. Mikhaylovskiy and F.E. Spada and T. Rasing and E.E. Fullerton and A.V. Kimel",
note = "{\textcopyright} 2019 American Physical Society ",
year = "2019",
month = aug,
day = "19",
doi = "10.1103/PhysRevMaterials.3.084415",
language = "English",
volume = "3",
journal = "Physical Review Materials",
issn = "2475-9953",
publisher = "American Physical Society",
number = "8",

}

RIS

TY - JOUR

T1 - THz emission from Co/Pt bilayers with varied roughness, crystal structure, and interface intermixing

AU - Li, G.

AU - Medapalli, R.

AU - Mikhaylovskiy, R.V.

AU - Spada, F.E.

AU - Rasing, T.

AU - Fullerton, E.E.

AU - Kimel, A.V.

N1 - © 2019 American Physical Society

PY - 2019/8/19

Y1 - 2019/8/19

N2 - Ultrafast demagnetization of Co/Pt heterostructures induced by a femtosecond 800-nm laser pulse launches a spin current from Co to Pt and subsequent conversion of the spin current to a charge current in the Pt layer due to the inverse spin-Hall effect. At the same time, due to the spin-dependent photogalvanic effect, a circularly polarized femtosecond laser pulse also generates a photocurrent at the Co/Pt interface. Both ultrashort photocurrent pulses are effectively detected in a contactless way by measuring the THz radiation they emit. Here we aim to understand how the properties of the Co/Pt interface affect the photocurrents in the bilayers. By varying the interfacial roughness, crystal structure, and interfacial intermixing, as well as having an explicit focus on the cases when THz emissions from these two photocurrents reveal opposite trends, we identify which interface properties play a crucial role for the photocurrents. In particular, we show that by reducing the roughness, the THz emission due to the spin-dependent photogalvanic effect reduces to zero while the strength of the THz emission from the photocurrent associated with the inverse spin-Hall effect increases by a factor of 2. On the other hand, while intermixing strongly enhances the THz emission from the inverse spin-Hall effect by a factor of 4.2, THz emission related to the spin-dependent photogalvanic effect reveals the opposite trend. These findings indicate that microstructural properties of the Co-Pt interface play a decisive role in the generation of photocurrents.

AB - Ultrafast demagnetization of Co/Pt heterostructures induced by a femtosecond 800-nm laser pulse launches a spin current from Co to Pt and subsequent conversion of the spin current to a charge current in the Pt layer due to the inverse spin-Hall effect. At the same time, due to the spin-dependent photogalvanic effect, a circularly polarized femtosecond laser pulse also generates a photocurrent at the Co/Pt interface. Both ultrashort photocurrent pulses are effectively detected in a contactless way by measuring the THz radiation they emit. Here we aim to understand how the properties of the Co/Pt interface affect the photocurrents in the bilayers. By varying the interfacial roughness, crystal structure, and interfacial intermixing, as well as having an explicit focus on the cases when THz emissions from these two photocurrents reveal opposite trends, we identify which interface properties play a crucial role for the photocurrents. In particular, we show that by reducing the roughness, the THz emission due to the spin-dependent photogalvanic effect reduces to zero while the strength of the THz emission from the photocurrent associated with the inverse spin-Hall effect increases by a factor of 2. On the other hand, while intermixing strongly enhances the THz emission from the inverse spin-Hall effect by a factor of 4.2, THz emission related to the spin-dependent photogalvanic effect reveals the opposite trend. These findings indicate that microstructural properties of the Co-Pt interface play a decisive role in the generation of photocurrents.

KW - Binary alloys

KW - Cobalt alloys

KW - Crystal symmetry

KW - Laser pulses

KW - Mixing

KW - Photocurrents

KW - Platinum

KW - Platinum alloys

KW - Terahertz waves

KW - Circularly polarized

KW - Interface intermixing

KW - Interface property

KW - Interfacial intermixing

KW - Interfacial roughness

KW - Micro-structural properties

KW - Photogalvanic effects

KW - Ultrafast demagnetization

KW - Spin Hall effect

U2 - 10.1103/PhysRevMaterials.3.084415

DO - 10.1103/PhysRevMaterials.3.084415

M3 - Journal article

VL - 3

JO - Physical Review Materials

JF - Physical Review Materials

SN - 2475-9953

IS - 8

M1 - 084415

ER -