Time-domain detection of current controlled magnetization damping in Pt/Ni81Fe19 bilayer and determination of Pt spin Hall angle

Ganguly, Arnab; Rowan-Robinson, Richard M.; Haldar, Arabinda; Jaiswal, Shashank; Sinha, Jaivardhan; Hindmarch, A. T.; Atkinson, D.; Barman, Anjan

doi:10.1063/1.4896277

Cited by 32 publications

(32 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Effective damping, in turn, gets modulated depending on the injected spin current density and relative orientation between the magnetic moment (which lies along the direction of magnetic field) and charge current density [24]. The modulation of damping (MOD) under the influence of spin current [28,43] can be expressed as:…”

Section: A Principle Behind the Determination Of Spin Hall Anglementioning

confidence: 99%

All-optical detection of the spin Hall angle inW/CoFeB/SiO2heterostructures with varying thickness of the tungsten layer

et al. 2017

View full text Add to dashboard Cite

The development of advanced spintronics devices hinges on the efficient generation and utilization of pure spin current. In materials with large spin-orbit coupling, the spin Hall effect may convert charge current to pure spin current and a large conversion efficiency, which is quantified by spin Hall angle (SHA), is desirable for the realization of miniaturized and energy efficient spintronic devices. Here, we report a giant SHA in beta-tungsten (β-W) thin films in Sub/W(t)/Co 20 Fe 60 B 20 (3 nm)/SiO 2 (2 nm) heterostructures with variable W thickness.We employed an all-optical time-resolved magneto-optical Kerr effect microscope for an unambiguous determination of SHA using the principle of modulation of Gilbert damping of the adjacent ferromagnetic layer by the spin-orbit torque from the W layer. A non-monotonic variation of SHA with W layer thickness (t) is observed with a maximum of about 0.4 at about t = 3 nm, followed by a sudden reduction to a very low value at t = 6 nm. This variation of SHA with W-thickness correlates well with the thickness dependent structural phase transition and resistivity variation of W above the spin diffusion length of W, while below this length the interfacial electronic effect at W/CoFeB influences the estimation of SHA.2

show abstract

Section: A Principle Behind the Determination Of Spin Hall Anglementioning

confidence: 99%

All-optical detection of the spin Hall angle inW/CoFeB/SiO2heterostructures with varying thickness of the tungsten layer

et al. 2017

View full text Add to dashboard Cite

show abstract

“…1 Indeed, SP effect driven by its versatility is being widely explored to determine spin to charge current conversion efficiency, referred as spin Hall angle (SH), in various kind of materials ranging from strong spin-orbit coupling system of heavy metals [2][3] , conventional semiconductors like (Si and Ge) [4][5] , wide-band gap semiconductor oxides (ZnO, ITO) [6][7] to ferromagnetic metallic alloys 3,8 oxides like SrRuO3 9 and even organic polymers 10 . In practice, other techniques of non-local injection in lateral spin valve structure 11 , spin-torque ferromagnetic resonance [12][13][14] and time-resolved magneto-optical Kerr effect 15 have also been established by various groups to measure SH of different materials. However very recent reports of significant modification in SP efficiency by further introducing complex interfacial effects [16][17] and novel application of SP effect to probe magnetic phase transitions in antiferromagnetic systems [18][19] undoubtedly highlight that it is a subject of intensive research with enormous possibilities.…”

Section: ___________________________ A)mentioning

confidence: 99%

Important role of magnetization precession angle measurement in inverse spin Hall effect induced by spin pumping

Gupta

Medwal

Kodama

et al. 2017

Applied Physics Letters

View full text Add to dashboard Cite

Here, we investigate spin Hall angle of Pt in Ni80Fe20/Pt bilayer system by using a broadband spin pumping and inverse spin Hall effect measurement. An out-of-plane excitation geometry with application of external magnetic field perpendicular to the charge current direction is utilized in order to suppress unwanted galvanomagnetic effects. Magnetization precession angle (C) on ferromagnetic resonance for wide excitation frequency range (4-14 GHz) is estimated from the rectification voltage of anisotropic magnetoresistance (AMR) and a conventional method of using microwave power in a coplanar waveguide. A marked difference in C profiles for the different methods is observed, resulting in the large variation in estimated values of spin current density at Ni80Fe20/Pt interface. The frequency dependence of the spin current density estimated using AMR effect is found to be similar to that of the inverse spin Hall voltage. We obtain the frequency-invariant spin Hall angle of 0.067  0.002. ___________________________ a)Electronic mail: sgupta@fukuma-lab.info, fukuma@cse.kyutech.ac.jp 2 Over the past decades large number of experimental as well as theoretical attempts have been made to construct new insights and applications of spin pumping (SP) effect since Tserkovnyak, et al. theoretically proposed the SP effect to inject pure spin current (JS) from a precessing ferromagnetic metal (FM) to neighboring normal metal (NM). 1 Indeed, SP effect driven by its versatility is being widely explored to determine spin to charge current conversion efficiency, referred as spin Hall angle (SH), in various kind of materials ranging from strong spin-orbit coupling system of heavy metals [2][3] , conventional semiconductors like (Si and Ge) [16][17] and novel application of SP effect to probe magnetic phase transitions in antiferromagnetic systems [18][19] undoubtedly highlight that it is a subject of intensive research with enormous possibilities.In a prototypical setup of spin pumping-inverse spin Hall effect (SP-ISHE) measurement, SP occurs during the excitation of ferromagnetic resonance (FMR) when precession of magnetization in FM injects pure spin current into adjacent NM layer and then the injected spin and Obstbaum et al. 22 Therefore, systematic and controlled studies of line shape analysis in different external magnetic field direction were performed in order to carefully distinguish ISHE induced dc voltage (VISHE) unambiguously from unwanted spurious signal. [22][23][24][25][26] However, in such studies, precession of the magnetization at FMR, i.e., the magnetization precession angle (C) and its trajectory [26][27] is not sufficiently characterized. It is important to estimate independently the precession angle (C) to have quantitative analysis of SH as SH ∝ VISHE / JS, where JS is being second order effect in the precession angle (sin 2 C). Moreover, waveguide based experimental set-up shows different microwave power losses and in-turn varying C values in the range of sweeping frequencies. Therefore thes...

show abstract

“…The femtosecond pulse train generated by a Ti: sapphire laser with a pulse duration of 50 fs and a repetition rate of 1 kHz was divided into pump and probe pulse beam. The pump pulse beam with a fluence of 3.54 mJ was focused to a spot of ~600 m in diameter on the sample to excite the magnetization precession, while the probe pulse beam with a fluence of 0.06 mJ was focused to a spot size of ~200 m in diameter and overlapped with the pump laser spot on the sample surface [16][17][18][19][20]. The Kerr rotation of reflected probe pulse beam was detected by a balanced detector.…”

Section: Methodsmentioning

confidence: 99%

The effect of growth sequence on magnetization damping in Ta/CoFeB/MgO structures

Liu

Huang

Gao

et al. 2018

Journal of Magnetism and Magnetic Materials

View full text Add to dashboard Cite

Abstract:Magnetization damping is a key parameter to control the critical current and the switching speed in magnetic random access memory, and here we report the effect of the growth sequence on the magnetic dynamics properties of perpendicularly magnetized Ta/CoFeB/MgO structures. Ultrathin CoFeB films have been grown between Ta and MgO but with different stack sequences, i.e. substrate/Ta/CoFeB/MgO/Ta and substrate/Ta/MgO/CoFeB/Ta. The magnetization dynamics induced by femtosecond laser was investigated by using all-optical pump-probe measurements. We found that the Gilbert damping constant was modulated by reversing stack structures, which offers the potential to tune the damping parameter by the growth sequence. The Gilbert damping constant was enhanced from 0.017 for substrate/Ta/CoFeB/MgO/Ta to 0.027 for substrate/Ta/MgO/CoFeB/Ta. We believe that this enhancement originates from the increase of intermixing at the CoFeB/Ta when the Ta atom layer was grown after the CoFeB layer.

show abstract

Time-domain detection of current controlled magnetization damping in Pt/Ni81Fe19 bilayer and determination of Pt spin Hall angle

Cited by 32 publications

References 23 publications

All-optical detection of the spin Hall angle inW/CoFeB/SiO2heterostructures with varying thickness of the tungsten layer

All-optical detection of the spin Hall angle inW/CoFeB/SiO2heterostructures with varying thickness of the tungsten layer

Important role of magnetization precession angle measurement in inverse spin Hall effect induced by spin pumping

The effect of growth sequence on magnetization damping in Ta/CoFeB/MgO structures

Contact Info

Product

Resources

About