Minimum Field Strength in Precessional Magnetization Reversal

Back, Christian; Allenspach, R.; Weber, W.; Parkin, S. S. P.; Weller, D.; Garwin, E. L.; Siegmann, H. C.

doi:10.1126/science.285.5429.864

Cited by 280 publications

(194 citation statements)

References 14 publications

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“…τ 0 is the typical time needed for an energy exchange between spin and lattice, and depends on the damping, the anisotropy constants and the magnetization 37 . It is usually estimated to about 10 ps.…”

Section: Saw Assisted Domain Nucleationmentioning

confidence: 99%

Irreversible magnetization switching using surface acoustic waves

et al. 2013

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An analytical and numerical approach is developped to pinpoint the optimal experimental conditions to irreversibly switch magnetization using surface acoustic waves (SAWs). The layers are magnetized perpendicular to the plane and two switching mechanisms are considered. In precessional switching, a small in-plane field initially tilts the magnetization and the passage of the SAW modifies the magnetic anisotropy parameters through inverse magneto-striction, which triggers precession, and eventually reversal. Using the micromagnetic parameters of a fully characterized layer of the magnetic semiconductor (Ga,Mn)(As,P), we then show that there is a large window of accessible experimental conditions (SAW amplitude/wave-vector, field amplitude/orientation) allowing irreversible switching. As this is a resonant process, the influence of the detuning of the SAW frequency to the magnetic system's eigenfrequency is also explored. Finally, another -non-resonantswitching mechanism is briefly contemplated, and found to be applicable to (Ga,Mn)(As,P): SAWassisted domain nucleation. In this case, a small perpendicular field is applied opposite the initial magnetization and the passage of the SAW lowers the domain nucleation barrier.

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Section: Saw Assisted Domain Nucleationmentioning

confidence: 99%

Irreversible magnetization switching using surface acoustic waves

et al. 2013

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“…It requires an overlapping pulse sequence for switching, but increases the thermal stability of bits and reduces the dipolar coupling between bits [3]. However, the dynamics at 1-10 GHz 4 Author to whom any correspondence should be addressed. of these exchange-coupled layers, which determines the highspeed response, is a fundamental limit to the increasing data rates in such magnetic storage devices [4].…”

Section: Introductionmentioning

confidence: 99%

“…However, the dynamics at 1-10 GHz 4 Author to whom any correspondence should be addressed. of these exchange-coupled layers, which determines the highspeed response, is a fundamental limit to the increasing data rates in such magnetic storage devices [4]. Therefore, understanding the nature and the extent of exchange interactions as well as their effect on the different excited modes in the GHz range is a technological key for such applications.…”

Section: Introductionmentioning

confidence: 99%

Microwave spectroscopy with vector network analyzer for interlayer exchange-coupled symmetrical and asymmetrical NiFe/Ru/NiFe

Belmeguenai¹,

Martin²,

Woltersdorf³

et al. 2008

J. Phys.: Condens. Matter

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Vector network analyzer ferromagnetic resonance spectroscopy (VNA-FMR) is used here to study the different excited modes of sputtered asymmetrical NiFe(13.6 nm)/Ru(d Ru )/ NiFe(27.2 nm) exchange-coupled films with variable Ru thicknesses. The obtained results have been compared to those of the symmetrical NiFe(30 nm)/Ru(d Ru )/NiFe(30 nm). In both cases, the measurements show the existence of an optic and an acoustic precessional mode. The optic mode was only observed over limited field ranges, especially in the symmetrical trilayers. To overcome such a limitation, we developed a new technique similar to the longitudinal FMR, where the bias and the rf field are parallel to each other and perpendicular to the pinning field. Interestingly, and in contrast to the symmetrical trilayers, we observed a mode anti-crossing in the dispersion relation of the asymmetrical layers that we attributed to the thickness difference between the two NiFe layers. Our experimental results on the effect of the biquadratic coupling on the mode frequency variations are in good agreement with the theory.

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“…The static Ruderman-Kittel-Kasuya-Yosida (RKKY) interlayer exchange between ferromagnets in magnetic multilayers [2] is suppressed in these devices by a sufficiently thick nonmagnetic spacer N or a tunnel barrier. The interest of the community shifts increasingly from the static to the dynamic properties of the magnetization [3]. This is partly motivated by curiosity, partly by the fact that the magnetization switching characteristics in memory devices is a real technological issue.…”

mentioning

confidence: 99%

Dynamic Exchange Coupling in Magnetic Bilayers

et al. 2003

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A long-ranged dynamic interaction between ferromagnetic films separated by normal-metal spacers is reported, which is communicated by nonequilibrium spin currents. It is measured by ferromagnetic resonance (FMR) and explained by an adiabatic spin-pump theory. In FMR the spin-pump mechanism of spatially separated magnetic moments leads to an appreciable increase in the FMR line width when the resonance fields are well apart, and results in a dramatic line-width narrowing when the FMR fields approach each other.PACS numbers: 75.40. Gb,75.70.Cn,76.50.+g,75.30.Et The giant magnetoresistance [1] accompanying realignment of magnetic configurations in metallic multilayers by an external magnetic field is routinely employed in magnetic read heads and is essential for high-density nonvolatile magnetic random-access memories. These typically consist of ferromagnetic/normal/ferromagnetic (F/N/F ) metal hybrid structures, i.e., magnetic bilayers which are an essential building block of the so called spin valves. The static Ruderman-Kittel-Kasuya-Yosida (RKKY) interlayer exchange between ferromagnets in magnetic multilayers [2] is suppressed in these devices by a sufficiently thick nonmagnetic spacer N or a tunnel barrier. The interest of the community shifts increasingly from the static to the dynamic properties of the magnetization [3]. This is partly motivated by curiosity, partly by the fact that the magnetization switching characteristics in memory devices is a real technological issue. A good grasp of the fundamental physics of the magnetization dynamics becomes of essential importance to sustain the exponential growth of device performance factors.In this Letter we study the largely unexplored dynamics of magnetic bilayers in a regime when there is no discernible static interaction between the magnetization vectors. Surprisingly, the magnetizations still turn out to be coupled, which we explain by emission and absorption of nonequilibrium spin currents. Under special conditions the two magnetizations are resonantly coupled by spin currents and carry out a synchronous motion, quite analogous to two connected pendulums. This dynamic interaction is an entirely new concept and physically very different from the static RKKY coupling. E.g., the former does not oscillate as a function of thickness and its range is exponentially limited by the spin-flip relaxation length of spacer layers and algebraically by the elastic mean free path. This coupling can have profound effects on magnetic relaxation and switching behavior in hybrid structures and devices.The unit vector m = M/M of the magnetization M(t) of a ferromagnet changes its direction in the presence of a noncollinear magnetic field. The motion of m in a single domain is described by the Landau-Lifshitz-Gilbert (LLG) equationwith γ being the absolute value of the gyromagnetic ratio. The first term on the right-hand side represents the torque induced by the effective magnetic field H eff = −∂F/∂M, where the free-energy functional F [M] consists of the Zeeman energy, ma...

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Minimum Field Strength in Precessional Magnetization Reversal

Cited by 280 publications

References 14 publications

Irreversible magnetization switching using surface acoustic waves

Irreversible magnetization switching using surface acoustic waves

Microwave spectroscopy with vector network analyzer for interlayer exchange-coupled symmetrical and asymmetrical NiFe/Ru/NiFe

Dynamic Exchange Coupling in Magnetic Bilayers

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