Correlation of the angular dependence of spin-transfer torque and giant magnetoresistance in the limit of diffusive transport in spin valves

Gmitra, Martin; Barnaś, J.

doi:10.1103/physrevb.79.012403

Cited by 16 publications

(18 citation statements)

References 19 publications

(35 reference statements)

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“…[77][78][79][80] for an extensive discussion of waviness where neither the parallel nor the antiparallel magnetic configuration is stable). The corresponding CRMT calculation is close, but below, to the wavy instability threshold 7,29,81 . This small discrepancy indicates a weakness of the effective TB approach as its physics is fairly sensitive to the choice of TB parameters.…”

Section: Interface Properties Of the Tb Modelmentioning

confidence: 99%

Multiscale approach to spin transport in magnetic multilayers

et al. 2011

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This article discusses two dual approaches to spin transport in magnetic multilayers: a direct, purely quantum, approach based on a Tight-Binding model (TB) and a semiclassical approach (Continuous Random Matrix Theory, CRMT). The combination of both approaches provides a systematic way to perform multi-scales simulations of systems that contain relevant physics at scales larger (spin accumulation, spin diffusion...) and smaller (specular reflexions, tunneling...) than the elastic mean free paths of the layers. We show explicitly that CRMT and TB give consistent results in their common domain of applicability.

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Section: Interface Properties Of the Tb Modelmentioning

confidence: 99%

Multiscale approach to spin transport in magnetic multilayers

et al. 2011

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“…When stabilized, it corresponds to a fast precessional state which forms a STO. In the context of voltage induced torque, these "wavy" structures, which do not require magnetic field in contrast to more conventional STOs, have been discussed for highly asymmetric spin valves [15][16][17]. Here we find that thermally induce STT corresponds to a wavy angular dependence of the torque in a much broader range of parameters.…”

mentioning

confidence: 58%

“…Although most STO require an external magnetic field, it was also discovered that STT can, in some very asymmetric spin-valves, stabilize an oscillating state in the absence of an external magnetic field. This is the so-called waviness [15][16][17]. In 2007, in one of the first article on "caloritronics", Bauer et al considered another route for creating STT via the combination of spintronics with thermoelectric effects[2]: the so-called thermal STT.…”

mentioning

confidence: 99%

Thermally driven magnetic precession in spin valves

Luc¹,

Waintal²

2014

Phys. Rev. B

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We investigate the angular dependence of the spin torque generated when applying a temperature difference across a spin-valve. Our study shows the presence of a non-trivial fixed point in this angular dependence, i.e. the possibility for a temperature gradient to stabilize radio frequency oscillations without the need for an external magnetic field. This so called "wavy" behavior can already be found upon applying a voltage difference across a spin-valve but we find that this effect is much more pronounced with a temperature difference. Our semi-classical theory is parametrized with experimentally measured parameters and allows one to predict the amplitude of the torque with good precision. Although thermal spin torque is by nature less effective than its voltage counterpart, we find that in certain geometries, temperature differences as low as a few degrees should be sufficient to trigger the switching of the magnetization.Spin caloritronics [1][2][3][4][5][6][7] studies the interplay of charge, spin and heat transport and provides extensions to some of the spintronics concepts. One of interest to us is the spin-transfer torque (STT) [8][9][10], first predicted by Slonczewski and Berger in 1996[11, 12]. STT is the angular momentum deposited by a spin-polarized current on a ferromagnetic layer. It is at the origin of interesting out of equilibrium dynamics for the magnetization layer leading to magnetic reversal or sustained RF oscillations. The later effect, known as spin-torque oscillator (STO) [13,14] is a promising candidate for agile RF sources. Although most STO require an external magnetic field, it was also discovered that STT can, in some very asymmetric spin-valves, stabilize an oscillating state in the absence of an external magnetic field. This is the so-called waviness [15][16][17]. In 2007, in one of the first article on "caloritronics", Bauer et al. considered another route for creating STT via the combination of spintronics with thermoelectric effects[2]: the so-called thermal STT. Spin-dependent thermoelectric effects soon started to attract some theoretical and experimental interest [4][5][6][18][19][20] In this letter, we investigate the angular dependence of the STT induced by temperature gradients applied across various type of magnetic spin valves. Our semi-classical theory, carefully tabulated with experimentally measured parameters, shows that thermally-induced STT is naturally "wavy" for a wide range of devices. By optimizing the geometry of the sample, we predict that magnetic switching can be obtained with temperature differences as low as a few degrees.Semi-classical drift-diffusion approach. Our starting point is a semi-classical approached for metallic magnetic multilayers that treats the charge degrees of freedom at the drift-diffusion level yet retains all the information about spin degrees of freedom [16,21]. This approach to which we refer as CRMT [16,21,22] (for Continuous Random Matrix Theory) can be seen as a generalization of the Valet Fert theory[23] to systems with non col...

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“…8 has taken into account this modification in ␤ and ␥ as well as the bulk and interfacial resistivities by introducing phenomenological constants that describe band-structure effects and parameters which take spin accumulation into consideration. The resistance of the structure, calculated for arbitrary noncollinear magnetic configurations 12,13 with the above-mentioned modifications indeed leads to changes in resistance with Py orientation that FIG. 7.…”

Section: Discussionmentioning

confidence: 99%

Thickness dependence and the role of spin transfer torque in nonlinear giant magnetoresistance of permalloy dual spin valves

et al. 2010

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Phys. Rev. Lett. 103, 237203 ͑2009͔͒ opens up the possibility for distinct physics which extends the standard model of giant magnetoresistance. When the outer ferromagnetic layers of a dual spin valve are antiparallel, the resulting accumulation of spin in the middle ferromagnetic layer strongly modifies its bulk and interfacial spin asymmetry and resistance. Here, we report experimental evidence of the role of bulk spin accumulation in this nonlinear effect and show that interfacial spin accumulation alone cannot account for the observed dependence of the effect on the thickness of the middle ferromagnetic layer. It is also shown that spin torque acting on the middle ferromagnetic layer combined with the nonlinear effect might be useful in understanding the dynamical features associated with the nonlinear behavior.

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Correlation of the angular dependence of spin-transfer torque and giant magnetoresistance in the limit of diffusive transport in spin valves

Cited by 16 publications

References 19 publications

Multiscale approach to spin transport in magnetic multilayers

Multiscale approach to spin transport in magnetic multilayers

Thermally driven magnetic precession in spin valves

Thickness dependence and the role of spin transfer torque in nonlinear giant magnetoresistance of permalloy dual spin valves

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