Ultrafast magnetization dynamics in high perpendicular anisotropy [Co∕Pt]n multilayers

Barman, Anjan; Wang, Suqin; Hellwig, Olav; Berger, Andreas; Fullerton, Eric E.; Schmidt, Holger

doi:10.1063/1.2709502

Cited by 147 publications

(95 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The intrinsic spin wave modes of single magnetic elements were measured using a previously described time-resolved magneto-optical Kerr microscope (TR-MOKE) [23]. The ultrafast pulses from a Coherent Mira Ti:Sapphire laser are split into pump (wavelengthfrequency-doubled 400 nm, ~10.6 mW/μm 2 ) and probe (wavelength -800 nm, ~2.65 mW/μm 2 )…”

Section: Methodsmentioning

confidence: 99%

Three-dimensional shape dependence of spin-wave modes in single FePt nanomagnets

et al. 2012

View full text Add to dashboard Cite

We report the dependence of the intrinsic spin wave spectra on the three-dimensional shape in single FePtnanomagnetic elements. In contrast to the well-known center and edge modes in flat, circular nanodisks, curved nanomagnets with identical nominal thickness and footprint exhibit a rich multi-mode spectrum with qualitatively different dependence on applied field, such as a low-frequency "pinned" mode. Dynamic micromagnetic modeling shows that the experimentally observed modes originate from different sections of the nanomagnet with vastly different demagnetization field. Thus, controlled shaping of a nanomagnet in all three dimensions creates the possibility of magnetization dynamics by design.2

show abstract

Section: Methodsmentioning

confidence: 99%

Three-dimensional shape dependence of spin-wave modes in single FePt nanomagnets

et al. 2012

View full text Add to dashboard Cite

show abstract

“…In such bilayer systems there are several mechanisms that may lead to the enhancement of damping. Spin-orbit coupling (SOC) and interfacial d-d hybridization enhance the intrinsic damping, while extrinsic enhancement of the damping can arise from two-magnon scattering processes, linked to roughness and defects at the interface region [1][2][3][11][12][13][14][15][16][17][18][19][20][21]. The total precessional damping is a sum of the intrinsic and extrinsic contributions.…”

Section: Introductionmentioning

confidence: 99%

Evolution of damping in ferromagnetic/nonmagnetic thin film bilayers as a function of nonmagnetic layer thickness

et al. 2016

View full text Add to dashboard Cite

Reprinted with permission from the American Physical Society: Azzawi, S. and Ganguly, A. and Toka c, M. and Rowan-Robinson, R.M. and Sinha, J. and Hindmarch, A.T. and Barman, A. and Atkinson, D. (2016) 'Evolution of damping in ferromagnetic/nonmagnetic thin lm bilayers as a function of nonmagnetic layer thickness.', Physical review B., 93 (5). 054402 c 2016 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modied, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. The evolution of damping in Co/Pt, Co/Au, and Ni 81 Fe 19 /Pt bilayers was studied with increasing nonmagnetic (NM) heavy-metal layer thicknesses in the range 0.2 nm t NM 10 nm, where t NM is the NM layer thickness. Magnetization precession was measured in the time domain using time-resolved magneto-optical Kerr effect magnetometry. Fitting of the data with a damped sinusoidal function was undertaken in order to extract the phenomenological Gilbert damping coefficient α. For Pt-capped Co and Ni 81 Fe 19 layers a large and complex dependence of α on the Pt layer thickness was observed, while for Au capping no significant dependence was observed. It is suggested that this difference is related to the different localized spin-orbit interaction related to intermixing and to d-d hybridization of Pt and Au at the interface with Co or Ni 81 Fe 19 . Also it was shown that damping is affected by the crystal structure differences in FM thin films and at the interface, which can modify the spin-diffusion length and the effective spin-mixing conductance. In addition to the intrinsic damping an extrinsic contribution plays an important role in the enhancement of damping when the Pt capping layer is discontinuous. The dependence of damping on the nonmagnetic layer thickness is complex but shows qualitative agreement with recent theoretical predictions.

show abstract

“…The question is still open whether the well developed theories can shed light on the damping behavior in such materials, and therefore motivates extensive research [31,[38][39][40][41][42][43]. For instance, S. Mizukami et al demonstrated a low value of α 0 with considerable K u in MnGa alloys, due to the low density of states at the Fermi level, D(E F ) [40].…”

Section: Introductionmentioning

confidence: 99%

Role of antisite disorder on intrinsic Gilbert damping inL10FePt films

et al. 2015

Phys. Rev. B

View full text Add to dashboard Cite

The impact of anti-site disorder x on the intrinsic Gilbert damping α 0 in well-ordered 1 FePt films is investigated by time-resolved magneto-optical Kerr effect. The variation of x mainly affects the electron scattering rate 1/τ e , while other leading parameters remain unchanged. The experimentally observed linear dependence of α 0 on 1/τ e indicates that spin relaxation is through electron interband transitions, as predicted by spin-orbit coupling torque correlation model. Measurements at low temperature show that α 0 remains unchanged with temperature even for FePt with very high chemical order, indicating that electron-phonon scattering is negligible. Moreover, as x decreases the perpendicular magnetic anisotropy increases and the Landau g factor exhibits a negative shift due to an increase in orbital momentum anisotropy. Our results will facilitate the design and exploration of new magnetic alloys with large magnetic anisotropy and desirable damping properties.PACS numbers: 75.78. Jp, 75.70.Tj, 75.50.Vv, 75.30.Gw + e-mail: hbzhao@fudan.edu.cn *e-mail: gxluep@wm.edu.[2] IntroductionUltrafast magnetization precessional switching in ferromagnets utilizing magnetic field pulses, spin polarized currents, and ultrafast laser pulses [1][2][3][4][5][6] is currently a popular topic due to its importance in magnetic information storage and spintronic applications. The uniform magnetization precession can be well modeled with Landau-Lifshitz-GilbertSlonczewski (LLGS) equation [7][8][9], where the Slonczewski torque term denotes the spin transfer torques (STTs), and the Gilbert damping parameter α determines the spin relaxation time [10] and is crucial for device performance [11][12][13][14]. The extrinsic Gilbert damping is due to nonlocal spin relaxation, such as spin pumping and magnon-magnon scattering, which can be tuned by artificial substrates, specially designed buffer and coverage layers [15][16][17][18][19][20][21], while the intrinsic Gilbert damping parameter α 0 is thought to arise from spin-orbit interaction (SOI) [22][23][24][25][26][27][28][29][30], and recently its quadratic dependence on SOI is demonstrated experimentally in FePtPd alloys [31].The α 0 describes the energy flow rate from spin to electronic orbital and phonon degrees of freedom through electron scattering, and has been studied in various theoretical models [22][23][24][25][26][27][28][29][30]. The breathing Fermi surface model [22] and torque-correlation model [23] based on first principle band structure calculations qualitatively match α 0 in soft magnetic alloys such as Fe, . Moreover, contributions to α 0 can be categorized based on intraband and interband transitions [23,26]. The damping rate from intraband transitions scales linearly with the electron relaxation time τ e and exhibits conductivity-like behavior. In contrast, the damping rate from the interband transition is proportional to the electron scattering rate 1/τ e , and consequently exhibits resistivity-like behavior. Therefore, the transition from conductivity-like to re...

show abstract

Ultrafast magnetization dynamics in high perpendicular anisotropy [Co∕Pt]n multilayers

Cited by 147 publications

References 27 publications

Three-dimensional shape dependence of spin-wave modes in single FePt nanomagnets

Three-dimensional shape dependence of spin-wave modes in single FePt nanomagnets

Evolution of damping in ferromagnetic/nonmagnetic thin film bilayers as a function of nonmagnetic layer thickness

Role of antisite disorder on intrinsic Gilbert damping inL10FePt films

Contact Info

Product

Resources

About