In this paper, we propose an approximate nonlinear theory of a spintronic terahertz-frequency emitter based on canted antiferromagnet-platinum bilayers. We present a model accounting for the excitation of nonlinear oscillations of the Néel vector in an antiferromagnet using terahertz pulses of an electromagnetic field. We determine that, with increasing amplitude of the pumping pulse, the spin system’s response increases nonlinearly in the fundamental quasiantiferromagnetic mode. We demonstrate control of the Néel vector trajectory by changing the terahertz pulse peak amplitude and frequency and determine the bands of nonlinear excitation using Fourier spectra. Finally, we develop an averaging method which gives the envelope function of an oscillating output electromagnetic field. The nonlinear dynamics of the antiferromagnet-based emitters discussed here is of importance in terahertz-frequency spintronic technologies.
REFERENCES
1.
P.
Němec
, M.
Fiebig
, T.
Kampfrath
, and A. V.
Kimel
, “Antiferromagnetic opto-spintronics
,” Nat. Phys.
14
, 1
(2018
). 2.
T.
Kampfrath
, A.
Sell
, G.
Klatt
, A.
Pashkin
, S.
Mährlein
, T.
Dekorsy
, M.
Wolf
, M.
Fiebig
, A.
Leitenstorfer
, and R.
Huber
, “Coherent terahertz control of antiferromagnetic spin waves
,” Nat. Photonics
5
, 31
(2011
). 3.
S.
Baierl
, J. H.
Mentink
, M.
Hohenleutner
, L.
Braun
, T.-M.
Do
, C.
Lange
, A.
Sell
, M.
Fiebig
, G.
Woltersdorf
, T.
Kampfrath
et al. “Terahertz-driven nonlinear spin response of antiferromagnetic nickel oxide
,” Phys. Rev. Lett.
117
, 197201
(2016
). 4.
R.
Khymyn
, I.
Lisenkov
, V.
Tiberkevich
, B. A.
Ivanov
, and A.
Slavin
, “Antiferromagnetic THz-frequency Josephson-like oscillator driven by spin current
,” Sci. Rep.
7
, 43705
(2017
). 5.
O.
Sulymenko
, O.
Prokopenko
, V.
Tiberkevich
, A.
Slavin
, B.
Ivanov
, and R.
Khymyn
, “Terahertz-frequency spin Hall auto-oscillator based on a canted antiferromagnet
,” Phys. Rev. Appl.
8
, 064007
(2017
). 6.
A.
Kirilyuk
, A. V.
Kimel
, and T.
Rasing
, “Laser-induced magnetization dynamics and reversal in ferrimagnetic alloys
,” Rep. Progress Phys.
76
, 026501
(2013
). 7.
P. S.
Keatley
, V.
Kruglyak
, P.
Gangmei
, and R.
Hicken
, “Ultrafast magnetization dynamics of spintronic nanostructures
,” Philos. Trans. R. Soc. A Math. Phys. Eng. Sci.
369
, 3115
–3135
(2011
). 8.
J.
Železný
, H.
Gao
, K.
Výborný
, J.
Zemen
, J.
Mašek
, A.
Manchon
, J.
Wunderlich
, J.
Sinova
, and T.
Jungwirth
, “Relativistic néel-order fields induced by electrical current in antiferromagnets
,” Phys. Rev. Lett.
113
, 157201
(2014
). 9.
A.
Kimel
, B.
Ivanov
, R.
Pisarev
, P.
Usachev
, A.
Kirilyuk
, and T.
Rasing
, “Inertia-driven spin switching in antiferromagnets
,” Nat. Phys.
5
, 727
(2009
). 10.
P.
Wadley
, B.
Howells
, J.
Železnỳ
, C.
Andrews
, V.
Hills
, R. P.
Campion
, V.
Novák
, K.
Olejník
, F.
Maccherozzi
, S.
Dhesi
et al. “Electrical switching of an antiferromagnet
,” Science
351
, 587
–590
(2016
). 11.
T.
Jungwirth
, X.
Marti
, P.
Wadley
, and J.
Wunderlich
, “Antiferromagnetic spintronics
,” Nat. Nanotechnol.
11
, 231
(2016
). 12.
D.
Bossini
, S.
Dal Conte
, Y.
Hashimoto
, A.
Secchi
, R.
Pisarev
, T.
Rasing
, G.
Cerullo
, and A.
Kimel
, “Macrospin dynamics in antiferromagnets triggered by sub-20 femtosecond injection of nanomagnons
,” Nat. Commun.
7
, 10645
(2016
). 13.
K.
Olejník
, V.
Schuler
, X.
Martí
, V.
Novák
, Z.
Kašpar
, P.
Wadley
, R. P.
Campion
, K. W.
Edmonds
, B. L.
Gallagher
, J.
Garcés
et al. “Antiferromagnetic cumnas multi-level memory cell with microelectronic compatibility
,” Nat. Commun.
8
, 15434
(2017
). 14.
T.
Seifert
, S.
Jaiswal
, U.
Martens
, J.
Hannegan
, L.
Braun
, P.
Maldonado
, F.
Freimuth
, A.
Kronenberg
, J.
Henrizi
, I.
Radu
et al. “Efficient metallic spintronic emitters of ultrabroadband terahertz radiation
,” Nat. Photonics.
10
, 483
(2016
). 15.
G.
Torosyan
, S.
Keller
, L.
Scheuer
, R.
Beigang
, and E. T.
Papaioannou
, “Optimized spintronic terahertz emitters based on epitaxial grown Fe/Pt layer structures
,” Sci. Rep.
8
, 1311
(2018
). 16.
D.
Yang
, J.
Liang
, C.
Zhou
, L.
Sun
, R.
Zheng
, S.
Luo
, Y.
Wu
, and J.
Qi
, “Powerful and tunable thz emitters based on the fe/pt magnetic heterostructure
,” Adv. Opt. Mater.
4
, 1944
–1949
(2016
). 17.
M.
Battiato
, K.
Carva
, and P. M.
Oppeneer
, “Superdiffusive spin transport as a mechanism of ultrafast demagnetization
,” Phys. Rev. Lett.
105
, 027203
(2010
). 18.
E.
Saitoh
, M.
Ueda
, H.
Miyajima
, and G.
Tatara
, “Conversion of spin current into charge current at room temperature: Inverse spin-Hall effect
,” Appl. Phys. Lett.
88
, 182509
(2006
). 19.
Y.
Tserkovnyak
, A.
Brataas
, and G. E. W.
Bauer
, “Enhanced gilbert damping in thin ferromagnetic films
,” Phys. Rev. Lett.
88
, 117601
(2002
). 20.
A.
Azevedo
, L.
Vilela Leão
, R.
Rodriguez-Suarez
, A.
Oliveira
, and S.
Rezende
, “dc effect in ferromagnetic resonance: Evidence of the spin-pumping effect?
,” J. Appl. Phys.
97
, 10C715
(2005
). 21.
H.
Jiao
and G. E. W.
Bauer
, “Spin backflow and ac voltage generation by spin pumping and the inverse spin Hall effect
,” Phys. Rev. Lett.
110
, 217602
(2013
). 22.
O.
Johansen
and A.
Brataas
, “Spin pumping and inverse spin Hall voltages from dynamical antiferromagnets
,” Phys. Rev. B
95
, 220408
(2017
). 23.
R.
Cheng
, J.
Xiao
, Q.
Niu
, and A.
Brataas
, “Spin pumping and spin-transfer torques in antiferromagnets
,” Phys. Rev. Lett.
113
, 057601
(2014
). 24.
I.
Dzyaloshinsky
, “A thermodynamic theory of “weak” ferromagnetism of antiferromagnetics
,” J. Phys. Chem. Solids
4
, 241
–255
(1958
). 25.
T.
Moriya
, “Anisotropic superexchange interaction and weak ferromagnetism
,” Phys. Rev.
120
, 91
(1960
). 26.
B.
Ivanov
, “Spin dynamics of antiferromagnets under action of femtosecond laser pulses
,” Low Temp. Phys
40
, 91
–105
(2014
). 27.
E.
Turov
, A.
Kolchanov
, V.
Men’shenin
, I.
Mirsaev
, and V.
Nikolaev
, Symmetry and Physical Properties of Antiferromagnets
(Fizmatlit
, Moscow
, 2001
).28.
S. A.
Gulbrandsen
and A.
Brataas
, “Spin transfer and spin pumping in disordered normal metal–antiferromagnetic insulator systems
,” Phys. Rev. B
97
, 054409
(2018
). 29.
J.
Walowski
and M.
Münzenberg
, “Perspective: Ultrafast magnetism and THz spintronics
,” J. Appl. Phys.
120
, 140901
(2016
). 30.
31.
H.
Nakayama
, K.
Ando
, K.
Harii
, T.
Yoshino
, R.
Takahashi
, Y.
Kajiwara
, K.-I.
Uchida
, Y.
Fujikawa
, and E.
Saitoh
, “Geometry dependence on inverse spin Hall effect induced by spin pumping in Ni 81 Fe 19/Pt films
,” Phys. Rev. B
85
, 144408
(2012
). 32.
R.
Mikhaylovskiy
, E.
Hendry
, A.
Secchi
, J. H.
Mentink
, M.
Eckstein
, A.
Wu
, R.
Pisarev
, V.
Kruglyak
, M.
Katsnelson
, T.
Rasing
et al. “Ultrafast optical modification of exchange interactions in iron oxides
,” Nat. Commun.
6
, 8190
(2015
). © 2019 Author(s).
2019
Author(s)
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