Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
CMOS compatible W/CoFeB/MgO spin Hall nano-oscillators with wide frequency tunability
Univ Gothenburg, Dept Phys, S-41296 Gothenburg, Sweden..
KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. NanOsc AB, S-16440 Kista, Sweden.ORCID-id: 0000-0003-3605-8872
Univ Gothenburg, Dept Phys, S-41296 Gothenburg, Sweden..
Univ Gothenburg, Dept Phys, S-41296 Gothenburg, Sweden..
Visa övriga samt affilieringar
2018 (Engelska)Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, nr 13, artikel-id 132404Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We demonstrate low-operational-current W/Co20Fe60B20/MgO spin Hall nano-oscillators (SHNOs) on highly resistive silicon (HiR-Si) substrates. Thanks to a record high spin Hall angle of the beta-phase W (theta(SH) = -0.53), a very low threshold current density of 3.3 x 10(7) A/cm(2) can be achieved. Together with their very wide frequency tunability (7-28GHz), promoted by a moderate perpendicular magnetic anisotropy, HiR-Si/W/CoFeB based SHNOs are potential candidates for wide-band microwave signal generation. Their CMOS compatibility offers a promising route towards the integration of spintronic microwave devices with other on-chip semiconductor microwave components.

Ort, förlag, år, upplaga, sidor
American Institute of Physics (AIP), 2018. Vol. 112, nr 13, artikel-id 132404
Nationell ämneskategori
Fysik
Identifikatorer
URN: urn:nbn:se:kth:diva-226793DOI: 10.1063/1.5022049ISI: 000429072800015Scopus ID: 2-s2.0-85044750620OAI: oai:DiVA.org:kth-226793DiVA, id: diva2:1203794
Forskningsfinansiär
Stiftelsen för strategisk forskning (SSF)VetenskapsrådetKnut och Alice Wallenbergs StiftelseEU, FP7, Sjunde ramprogrammet, 307144
Anmärkning

QC 20180504

Tillgänglig från: 2018-05-04 Skapad: 2018-05-04 Senast uppdaterad: 2018-09-07Bibliografiskt granskad
Ingår i avhandling
1. Linear, Non-Linear, and Synchronizing Spin Wave Modes in Spin Hall Nano-Oscillators
Öppna denna publikation i ny flik eller fönster >>Linear, Non-Linear, and Synchronizing Spin Wave Modes in Spin Hall Nano-Oscillators
2018 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Spin Hall nano-oscillators (SHNOs) are nanoscale spintronic devices that generate microwave signals with highly tunable frequency. This thesis focuses on improving the signal quality of nanoconstriction-based SHNOs and also on developing a better understanding of their magnetization dynamics.

In the first part of the thesis, we fabricate and characterize low-threshold current SHNOs using NiFe/β-W bilayers. Due to the high spin Hall angle of the β-phase W, the auto-oscillation threshold current is improved by 60% over SHNOs based on NiFe/Pt. We also demonstrate low operational current by utilizing W/Co20Fe60B20/MgO stacks on highly resistive silicon substrates. Thanks to the moderate perpendicular magnetic anisotropy (PMA) of Co20Fe60B20, these SHNOs show much wider frequency tunability than SHNOs based on NiFe with no PMA. Performance is further improved by using highly resistive silicon substrates with a high heat conductance, dissipating the generated excess heat much better than sapphire substrates. Moreover, it also means that the fabrication of SHNOs is now compatible with conventional CMOS fabrication, which is necessary if SHNOs are to be used in integrated circuits. In another approach, we attempt to decrease the threshold current of SHNOs based on an NiFe/Pt stack by inserting an ultra-thin Hf layer in the middle of the stack. This Hf dusting decreases the damping of the bilayer linearly but also degrades its spin Hall efficiency. These opposing trends determine the optimum Hf thickness to ≈0.4 nm, at which the auto-oscillation threshold current is minimum. Our achievements arising from these three approaches show a promising path towards the realization of low-current SHNO microwave devices with highly efficient spin-orbit torque.

In the next chapter, we use both electrical experimentation and micromagnetic simulation to study the auto-oscillating spin wave modes in nanoconstriction-based SHNOs as a function of the drive current and the applied field. First, we investigate the modes under an in-plane low-range field of 40-80 mT, which is useful for developing low-field spintronic devices with applications in microwave signal generation. It is also essential for future studies on the synchronization of multiple SHNOs. Next, using an out-of-plane applied magnetic field, we observe three different modes and demonstrate switching between them under a fixed external field by tuning only the drive current. The flexibility of these nanopatterned spin Hall nano-oscillators is desirable for implementing oscillator-based neuromorphic computing devices.

In the final part, we study the synchronization of multiple nanoconstriction-based SHNOs in weak in-plane fields. We electrically investigate the synchronization versus the angle of the field, observing synchronization for angles below a threshold angle. In agreement with the experimental results, the spatial profile of the spin waves from the simulations shows that the relative angle between the modes from the nanoconstrictions decreases with decreasing the field angle, thus facilitating synchronization. The synchronization observed at low in-plane fields improves the microwave signal quality and could also be useful for applications such as neuromorphic computing.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2018. s. 58
Serie
TRITA-SCI-FOU ; 2018:37
Nyckelord
spin Hall effect, spin Hall nano-oscillators, threshold current, microwave, spin wave, synchronization
Nationell ämneskategori
Den kondenserade materiens fysik
Forskningsämne
Fysik
Identifikatorer
urn:nbn:se:kth:diva-234657 (URN)978-91-7729-929-5 (ISBN)
Disputation
2018-10-05, Sal Sven-Olof Öhrvik, Kistagången 16, Electrum 1, floor 2, KTH Kista, Stockholm, 13:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20180907

Tillgänglig från: 2018-09-07 Skapad: 2018-09-07 Senast uppdaterad: 2018-09-10Bibliografiskt granskad

Open Access i DiVA

fulltext(1070 kB)11 nedladdningar
Filinformation
Filnamn FULLTEXT01.pdfFilstorlek 1070 kBChecksumma SHA-512
7b8f4b8cd5c1b482532eb79f8d76240748d45b738a86fdacf584b7a1d3e6f68147582200669af2fb0d765f72f512747d6a3e0ab80e24e3345e0c2f2ff0d817e9
Typ fulltextMimetyp application/pdf

Övriga länkar

Förlagets fulltextScopushttps://aip.scitation.org/doi/abs/10.1063/1.5022049

Personposter BETA

Mazraati, HamidJiang, ShengÅkerman, Johan

Sök vidare i DiVA

Av författaren/redaktören
Mazraati, HamidJiang, ShengÅkerman, Johan
Av organisationen
Tillämpad fysikMaterial- och nanofysik
I samma tidskrift
Applied Physics Letters
Fysik

Sök vidare utanför DiVA

GoogleGoogle Scholar
Totalt: 11 nedladdningar
Antalet nedladdningar är summan av nedladdningar för alla fulltexter. Det kan inkludera t.ex tidigare versioner som nu inte längre är tillgängliga.

doi
urn-nbn

Altmetricpoäng

doi
urn-nbn
Totalt: 94 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf