Study of fully epitaxial Fe/Pt bilayers for spin pumping by ferromagnetic resonance spectroscopy

Conca, A.; Keller, Sascha; Mihalceanu, Laura; Kehagias, Th.; Dimitrakopulos, G. P.; Hillebrands, B.; Papaioannou, Evangelos Th.

doi:10.1103/physrevb.93.134405

Cited by 68 publications

(62 citation statements)

References 35 publications

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“…1(a)-(b) can prove the epitaxial growth of the Pt and Fe layers, and the X-ray diffraction measurement shows the diffraction peak of Pt(002), indicating the epitaxy relation of Pt<100>(001)//Fe<110>(001). 6,12 In order to study the Pt-thickness dependent absorption spectrum, the Pt layer was grown into the step shape with 8 different thickness, thus the Fe/Pt bilayers with different Pt thickness are prepared under the same condition, which can provide the same film quality and the same Fe/Pt interface for all the Fe/Pt bilayers. The samples were aligned on top of the signal line of a G-S-G co-planar waveguide (CPW) with the easy axis of Fe film along the longitudinal direction, then the transmission parameter S21 was measured via the vector network analyzer.…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, the single crystalline system has stronger crystalline anisotropy, which could further influence the spin dynamic properties. Recently, Papaioannou et al studied the spin pumping in single crystalline Fe/Pt, and optimized the spin mixing conductance at the interface by controlling the growth temperature, 6,12 but there was no report on the spin diffusion length and θ SH in single-crystalline Pt film, which could be essential for further understanding of spin dynamics.…”

Section: Introductionmentioning

confidence: 99%

“…As the spin current generated in the adjacent layer, the damping of ferromagnetic material will be enhanced, 2-7 and the enhanced damping can be used to extract the spin diffusion length and the spin mixing conductance. [2][3][4][5][6][7] Moreover, the spin current in the heavy normal metal (NM) can be converted to a charge current through the inverse spin hall effect (ISHE). 8 The ISHE has been broadly studied, [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] and in general ferromagnetic metal (FM)/NM system, the ISHE is mixing with the spin rectification effect (SRE), which is induced by the anisotropic magneto-resistance (AMR).…”

Section: Introductionmentioning

confidence: 99%

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Spin pumping and the inverse spin hall effect in single crystalline Fe/Pt heterostructure

et al. 2017

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Spin pumping effect in single crystalline Fe/Pt bilayer has been systematically studied by the measurements of the microwave absorption spectrum and the inverse spin hall voltage detection. The gilbert damping constant of Fe first increases with Pt thickness and then saturates at tPt>1.5 nm. The spin diffusion length can be determined as 1.5±0.4 nm, and the spin mixing conductance is (3.4±0.4)×1019 m-2. The inverse spin hall voltage is quantitatively separated from the spin rectification effect through the measurement of the magnetization angular dependence, and the estimated spin hall angle of Pt is 0.048±0.015, in consistent with the values determined in polycrystalline Pt films.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spin pumping and the inverse spin hall effect in single crystalline Fe/Pt heterostructure

et al. 2017

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“…In addition, it affects the damping properties critically by various seed and capping layers. Recently, research has been focussed to understand the effect of heavy metal as seed and capping layers [17][18][19][20][21][22]. In a recent report Tokac et al [21] have shown that the effective spin conductance mixing strongly depends on the interfaces of seed (Ta/Cu) and capping (Cu or Ir) layers.…”

Section: Introductionmentioning

confidence: 99%

Study of spin pumping in Co thin film vis-à-vis seed and capping layers using ferromagnetic resonance spectroscopy

Singh

Jena

2017

J. Phys. D: Appl. Phys.

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Abstract:We investigated the dependence of the seed (Ta/Pt, Ta/Au) and capping (Pt/Ta, Au/Ta) layers on spin pumping effect in the ferromagnetic 3 nm thick Co thin film using ferromagnetic resonance spectroscopy. The data is fitted with Kittel's equation to evaluate damping constant and g-factor. A strong dependence of seed and capping layers on spin pumping has been discussed. The value of damping constant (α) is found to be relatively large i.e. 0.0326±0.0008 for the Ta(3)/Pt(3)/Co(3)/Pt(3)/Ta(3) (nm) multilayer structure, while it is 0.0104±0.0003 for Ta(3)/Co(3)/Ta(3) (nm). Increase in α is observed due to Pt layer that works as a good sink for spins due to high spin orbit coupling. In addition, we measured the effective spin conductance  g = 2.00 ± 0.08 × 10 18 m -2 for the tri-layer structure Pt(3)/Co(3)/Pt(3) (nm) as a result of the enhancement in α relative to its bulk value.We observed that the evaluated g-factor decreases as effective demagnetizing magnetic field increases in all the studied samples. The azimuthal dependence of magnetic resonance field and line width showed relatively high anisotropy in the tri-layer Ta(3)/Co(3)/Ta(3) (nm) structure.

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“…For this, the samples were placed face down and the S 12 transmission parameter was recorded. A more detailed description of the FMR measurement and analysis procedure is shown in previous work [11,12]. Brillouin light spectroscopy (BLS) was additionally used for the measurement of the exchange constant.…”

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confidence: 99%

CoFeAlB alloy with low damping and low magnetization as a candidate for spin transfer torque switching

Conca

Nakano

Meyer

et al. 2017

Journal of Applied Physics

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We investigate the effect of Al doping on the magnetic properties of the alloy CoFeB. Comparative measurements of the saturation magnetization, the Gilbert damping parameter α and the exchange constant as a function of the annealing temperature for CoFeB and CoFeAlB thin films are presented. Our results reveal a strong reduction of the magnetization for CoFeAlB in comparison to CoFeB. If the prepared CoFeAlB films are amorphous, the damping parameter α is unaffected by the Al doping in comparison to the CoFeB alloy. In contrast, in the case of a crystalline CoFeAlB film, α is found to be reduced. Furthermore, the x-ray characterization and the evolution of the exchange constant with the annealing temperature indicate a similar crystallization process in both alloys. The data proves the suitability of CoFeAlB for spin torque switching properties where a reduction of the switching current in comparison with CoFeB is expected.The alloy CoFeB is widely used in magnetic tunneling junctions in combination with MgO barriers due to the large magnetoresistance effect originating in the spin filtering effect [1][2][3][4]. For the application in magnetic random access memories, the switching of the magnetization of the free layer via spin transfer torque (STT) with spin polarised currents is a key technology. However, the required currents for the switching process are still large and hinder the applicability of this technique. The critical switching current density for an in-plane magnetized system is given by [5]where e is the electron charge, α is the Gilbert damping parameter, M S is the saturation magnetization, t f is the thickness of the free layer, H ext is the external field, H K is the effective anisotropy field and η is the spin transfer efficiency. From the expression it is clear that, concerning material parameters, J c0 is ruled by the product αM 2 S . For out-of-plane oriented layers, the term 2πM S vanishes and then J C0 is proportional to αM S [6]. Even in the case of using pure spin currents created by the Spin Hall effect, the required currents are proportional to factors of the form α n M S with n = 1, 1/2 [7]. A proper strategy to reduce the critical switching currents is then defined by reducing the saturation magnetization. This can be achieved by the development of new materials or the modification of known materials with promising properties. Since the compatibility with a MgO tunneling barrier and the spin filtering effect must be guaranteed together with industrial applicability, the second option is clearly an advantage by reducing M S in the CoFeB alloy. In this case, a critical point is that this reduction must not be associated with an increase of the damping parameter α.

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Study of fully epitaxial Fe/Pt bilayers for spin pumping by ferromagnetic resonance spectroscopy

Cited by 68 publications

References 35 publications

Spin pumping and the inverse spin hall effect in single crystalline Fe/Pt heterostructure

Spin pumping and the inverse spin hall effect in single crystalline Fe/Pt heterostructure

Study of spin pumping in Co thin film vis-à-vis seed and capping layers using ferromagnetic resonance spectroscopy

CoFeAlB alloy with low damping and low magnetization as a candidate for spin transfer torque switching

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