We study the current tunable microwave signal properties of nano-constriction-based spin Hall nano-oscillators in oblique magnetic fields as a function of the nano-constriction width, nm. The threshold current is found to scale linearly with w, defining a constant threshold current density of 1.7 × 108 A/cm2. While the current dependence of the microwave frequency shows the same generic nonmonotonic behavior for all 80 nm, the quality of the generated microwave signal improves strongly with w, as the total power increases and the linewidth decreases linearly with w. As a consequence, the peak power for a 140 nm nano-constriction is about an order of magnitude higher than that for an 80 nm nano-constriction. The smallest nano-constriction, 50 nm, exhibits a different behavior with a higher power and a worse linewidth, indicating a crossover into a qualitatively different narrow-constriction regime.
References
1.
V. E.
Demidov
, S.
Urazhdin
, H.
Ulrichs
, V.
Tiberkevich
, A.
Slavin
, D.
Baither
, G.
Schmitz
, and S. O.
Demokritov
, “Magnetic nano-oscillator driven by pure spin current
,” Nat. Mater.
11
, 1028
–1031
(2012
).2.
L.
Liu
, C.-F.
Pai
, D. C.
Ralph
, and R. A.
Buhrman
, “Magnetic oscillations driven by the spin Hall effect in 3-terminal magnetic tunnel junction devices
,” Phys. Rev. Lett.
109
, 186602
(2012
).3.
R. H.
Liu
, W. L.
Lim
, and S.
Urazhdin
, “Spectral characteristics of the microwave emission by the spin Hall nano-oscillator
,” Phys. Rev. Lett.
110
, 147601
(2013
).4.
V. E.
Demidov
, H.
Ulrichs
, S. V.
Gurevich
, S. O.
Demokritov
, V. S.
Tiberkevich
, A. N.
Slavin
, A.
Zholud
, and S.
Urazhdin
, “Synchronization of spin Hall nano-oscillators to external microwave signals
,” Nat. Commun.
5
, 3179
(2014
).5.
H.
Ulrichs
, V. E.
Demidov
, and S. O.
Demokritov
, “Micromagnetic study of auto-oscillation modes in spin-Hall nano-oscillators
,” Appl. Phys. Lett.
104
, 042407
(2014
).6.
Z.
Duan
, A.
Smith
, L.
Yang
, B.
Youngblood
, J.
Lindner
, V. E.
Demidov
, S. O.
Demokritov
, and I. N.
Krivorotov
, “Nanowire spin torque oscillator driven by spin orbit torques
,” Nat. Commun.
5
, 5616
(2014
).7.
V. E.
Demidov
, S.
Urazhdin
, A.
Zholud
, A. V.
Sadovnikov
, and S. O.
Demokritov
, “Nanoconstriction-based spin-Hall nano-oscillator
,” Appl. Phys. Lett.
105
, 172410
(2014
).8.
M.
Ranjbar
, P.
Dürrenfeld
, M.
Haidar
, E.
Iacocca
, M.
Balinskiy
, T.
Le
, M.
Fazlali
, A.
Houshang
, A.
Awad
, R.
Dumas
, and J.
Åkerman
, “CoFeB-based spin Hall nano-oscillators
,” IEEE Magn. Lett.
5
, 1
(2014
).9.
M.
Madami
, G.
Gubbiotti
, T.
Moriyama
, K.
Tanaka
, G.
Siracusano
, M.
Carpentieri
, G.
Finocchio
, S.
Tacchi
, T.
Ono
, and G.
Carlotti
, “Micro-focused Brillouin light scattering study of the magnetization dynamics driven by spin Hall effect in a transversely magnetized NiFe nanowire
,” J. Appl. Phys.
117
, 17D504
(2015
).10.
H.
Mazraati
, S.
Chung
, A.
Houshang
, M.
Dvornik
, L.
Piazza
, F.
Qejvanaj
, S.
Jiang
, T. Q.
Le
, J.
Weissenrieder
, and J.
Åkerman
, “Low operational current spin Hall nano-oscillators based on NiFe/W bilayers
,” Appl. Phys. Lett.
109
, 242402
(2016
).11.
T.
Chen
, R. K.
Dumas
, A.
Eklund
, P. K.
Muduli
, A.
Houshang
, A. A.
Awad
, P.
Dürrenfeld
, B. G.
Malm
, A.
Rusu
, and J.
Åkerman
, “Spin-torque and spin-Hall nano-oscillators
,” Proc. IEEE
104
, 1919
–1945
(2016
).12.
B.
Divinskiy
, V.
Demidov
, A.
Kozhanov
, A.
Rinkevich
, S.
Demokritov
, and S.
Urazhdin
, “Nanoconstriction spin-Hall oscillator with perpendicular magnetic anisotropy
,” Appl. Phys. Lett.
111
, 032405
(2017
).13.
V.
Demidov
, S.
Urazhdin
, G.
De Loubens
, O.
Klein
, V.
Cros
, A.
Anane
, and S.
Demokritov
, “Magnetization oscillations and waves driven by pure spin currents
,” Phys. Rep.
673
, 1
–31
(2017
).14.
M.
Zahedinejad
, H.
Mazraati
, H.
Fulara
, J.
Yue
, S.
Jiang
, A. A.
Awad
, and J.
Åkerman
, “CMOS compatible W/CoFeB/MgO spin Hall nano-oscillators with wide frequency tunability
,” Appl. Phys. Lett.
112
, 132404
–132405
(2018
).15.
H.
Mazraati
, S. R.
Etesami
, S. A. H.
Banuazizi
, S.
Chung
, A.
Houshang
, A. A.
Awad
, M.
Dvornik
, and J.
Åkerman
, “Auto-oscillating spin-wave modes of constriction-based spin Hall nano-oscillators in weak in-plane fields
,” Phys. Rev. Appl.
10
, 054017
(2018
).16.
N.
Sato
, K.
Schultheiss
, L.
Körber
, N.
Puwenberg
, T.
Mühl
, A. A.
Awad
, S. S.
Arekapudi
, O.
Hellwig
, J.
Fassbender
, and H.
Schultheiss
, “Domain wall based spin-Hall nano-oscillators
,” Phys. Rev. Lett.
123
, 57204
(2019
).17.
M.
Tarequzzaman
, T.
Böhnert
, M.
Decker
, J. D.
Costa
, J.
Borme
, B.
Lacoste
, E.
Paz
, A. S.
Jenkins
, S.
Serrano-Guisan
, C. H.
Back
, R.
Ferreira
, and P. P.
Freitas
, “Spin torque nano-oscillator driven by combined spin injection from tunneling and spin Hall current
,” Commun. Phys.
2
, 20
(2019
).18.
B.
Divinskiy
, V.
Demidov
, S.
Urazhdin
, R.
Freeman
, A.
Rinkevich
, and S.
Demokritov
, “Controllable excitation of quasi-linear and bullet modes in a spin-Hall nano-oscillator
,” Appl. Phys. Lett.
114
, 042403
(2019
).19.
L.
Chen
, S.
Urazhdin
, Y.
Du
, and R.
Liu
, “Dynamical mode coupling and coherence in a spin Hall nano-oscillator with perpendicular magnetic anisotropy
,” Phys. Rev. Appl.
11
, 064038
(2019
).20.
L.
Chen
, K.
Zhou
, S.
Urazhdin
, W.
Jiang
, Y.
Du
, and R.
Liu
, “Dynamical mode coexistence and chaos in a nanogap spin Hall nano-oscillator
,” Phys. Rev. B
100
, 104436
(2019
).21.
J. E.
Hirsch
, “Spin Hall effect
,” Phys. Rev. Lett.
83
, 1834
–1837
(1999
).22.
A.
Hoffmann
, “Spin Hall effects in metals
,” IEEE Trans. Magn.
49
, 5172
–5193
(2013
).23.
J.
Sinova
, S. O.
Valenzuela
, J.
Wunderlich
, C. H.
Back
, and T.
Jungwirth
, “Spin Hall effects
,” Rev. Mod. Phys.
87
, 1213
–1260
(2015
).24.
J. C.
Slonczewski
, “Current-driven excitation of magnetic multilayers
,” J. Magn. Magn. Mater.
159
, L1
–L7
(1996
).25.
L.
Berger
, “Emission of spin waves by a magnetic multilayer traversed by a current
,” Phys. Rev. B
54
, 9353
–9358
(1996
).26.
D. C.
Ralph
and M. D.
Stiles
, “Spin transfer torques
,” J. Magn. Magn. Mater.
320
, 1190
–1216
(2008
).27.
A. A.
Awad
, P.
Dürrenfeld
, A.
Houshang
, M.
Dvornik
, E.
Iacocca
, R. K.
Dumas
, and J.
Åkerman
, “Long-range mutual synchronization of spin Hall nano-oscillators
,” Nat. Phys.
13
, 292
–299
(2017
).28.
P.
Dürrenfeld
, A. A.
Awad
, A.
Houshang
, R. K.
Dumas
, and J.
Åkerman
, “A 20 nm spin Hall nano-oscillator
,” Nanoscale
9
, 1285
–1291
(2017
).29.
B.
Divinskiy
, S.
Urazhdin
, V. E.
Demidov
, A.
Kozhanov
, A. P.
Nosov
, A. B.
Rinkevich
, and S. O.
Demokritov
, “Magnetic droplet solitons generated by pure spin currents
,” Phys. Rev. B
96
, 224419
(2017
).30.
H.
Fulara
, M.
Zahedinejad
, R.
Khymyn
, A. A.
Awad
, S.
Muralidhar
, M.
Dvornik
, and J.
Åkerman
, “Spin-orbit torque-driven propagating spin waves
,” Sci. Adv.
5
, eaax8467
(2019
).31.
B.
Divinskiy
, V. E.
Demidov
, S.
Urazhdin
, R.
Freeman
, A. B.
Rinkevich
, and S. O.
Demokritov
, “Excitation and amplification of spin waves by spin–orbit torque
,” Adv. Mater.
30
, 1802837
(2018
).32.
M.
Zahedinejad
, A. A.
Awad
, P.
Durrenfeld
, A.
Houshang
, Y.
Yin
, P. K.
Muduli
, and J.
Akerman
, “Current modulation of nanoconstriction spin-Hall nano-oscillators
,” IEEE Magn. Lett.
8
, 1
–4
(2017
).33.
T.
Hache
, T.
Weinhold
, K.
Schultheiss
, J.
Stigloher
, F.
Vilsmeier
, C.
Back
, S. S.
Arekapudi
, O.
Hellwig
, J.
Fassbender
, and H.
Schultheiss
, “Combined frequency and time domain measurements on injection-locked, constriction-based spin Hall nano-oscillators
,” Appl. Phys. Lett.
114
, 102403
(2019
).34.
M.
Zahedinejad
, A. A.
Awad
, S.
Muralidhar
, R.
Khymyn
, H.
Fulara
, H.
Mazraati
, M.
Dvornik
, and J.
Åkerman
, “Two-dimensional mutually synchronized spin Hall nano-oscillator arrays for neuromorphic computing
,” Nat. Nanotechnol.
15
, 47
(2020
).35.
M.
Dvornik
, A. A.
Awad
, and J.
Åkerman
, “Origin of magnetization auto-oscillations in constriction-based spin Hall nano-oscillators
,” Phys. Rev. Appl.
9
, 014017
(2018
).36.
A.
Slavin
and V.
Tiberkevich
, “Nonlinear auto-oscillator theory of microwave generation by spin-polarized current
,” IEEE Trans. Magn.
45
, 1875
–1918
(2009
).37.
G.
Gerhart
, E.
Bankowski
, G. A.
Melkov
, V. S.
Tiberkevich
, and A. N.
Slavin
, “Angular dependence of the microwave-generation threshold in a nanoscale spin-torque oscillator
,” Phys. Rev. B
76
, 024437
(2007
).38.
J. V.
Kim
, V.
Tiberkevich
, and A. N.
Slavin
, “Generation linewidth of an auto-oscillator with a nonlinear frequency shift: Spin-torque nano-oscillator
,” Phys. Rev. Lett.
100
, 017207
(2008
).39.
V. S.
Tiberkevich
, R. S.
Khymyn
, H. X.
Tang
, and A. N.
Slavin
, “Sensitivity to external signals and synchronization properties of a non-isochronous auto-oscillator with delayed feedback
,” Sci. Rep.
4
, 3873
(2015
).© 2020 Author(s).
2020
Author(s)
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