Spin-current interaction with a monodomain magnetic body: A model study
IBM1
TL;DR: In this paper, the authors examined the consequence of spin-current-induced angular momentum deposition in a monodomain Stoner-Wohlfarth magnetic body using the Landau-Lifshitz-Gilbert equation with a phenomenological damping coefficient.
Abstract: I examined the consequence of a spin-current-induced angular momentum deposition in a monodomain Stoner-Wohlfarth magnetic body. The magnetic dynamics of the particle are modeled using the Landau-Lifshitz-Gilbert equation with a phenomenological damping coefficient $\ensuremath{\alpha}.$ Two magnetic potential landscapes are studied in detail: One uniaxial, the other uniaxial in combination with an easy-plane potential term that could be used to model a thin-film geometry with demagnetization. Quantitative predictions are obtained for comparison with experiments.
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TL;DR: Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems as discussed by the authors, where the primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport.
Abstract: Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.
9,158 citations
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...This phenomenon, known as spin-transfer torque, has since been extensively studied both theoretically and experimentally (Bazaliy et al., 1998; Myers et al., 1999; Stiles and Zangwill, 2002; Sun, 2000; Tsoi et al., 1998; Waintal et al., 2000) and current-induced magnetization reversal was demonstrated at room temperature (Katine et al....
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...…torque, has since been extensively studied both theoretically and experimentally (Bazaliy et al., 1998; Tsoi et al., 1998; Myers et al., 1999; Sun, 2000; Waintal et al., 2000; Stiles and Zangwill, 2002), and current-induced magnetization reversal has been demonstrated at room temperature…...
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TL;DR: In this paper, a giant spin Hall effect (SHE) in β-tantalum was shown to generate spin currents intense enough to induce spin-torque switching of ferromagnets at room temperature.
Abstract: Spin currents can apply useful torques in spintronic devices. The spin Hall effect has been proposed as a source of spin current, but its modest strength has limited its usefulness. We report a giant spin Hall effect (SHE) in β-tantalum that generates spin currents intense enough to induce efficient spin-torque switching of ferromagnets at room temperature. We quantify this SHE by three independent methods and demonstrate spin-torque switching of both out-of-plane and in-plane magnetized layers. We furthermore implement a three-terminal device that uses current passing through a tantalum-ferromagnet bilayer to switch a nanomagnet, with a magnetic tunnel junction for read-out. This simple, reliable, and efficient design may eliminate the main obstacles to the development of magnetic memory and nonvolatile spin logic technologies.
3,330 citations
TL;DR: The authors are starting to see a new paradigm where magnetization dynamics and charge currents act on each other in nanostructured artificial materials, allowing faster, low-energy operations: spin electronics is on its way.
Abstract: Electrons have a charge and a spin, but until recently these were considered separately. In classical electronics, charges are moved by electric fields to transmit information and are stored in a capacitor to save it. In magnetic recording, magnetic fields have been used to read or write the information stored on the magnetization, which 'measures' the local orientation of spins in ferromagnets. The picture started to change in 1988, when the discovery of giant magnetoresistance opened the way to efficient control of charge transport through magnetization. The recent expansion of hard-disk recording owes much to this development. We are starting to see a new paradigm where magnetization dynamics and charge currents act on each other in nanostructured artificial materials. Ultimately, 'spin currents' could even replace charge currents for the transfer and treatment of information, allowing faster, low-energy operations: spin electronics is on its way.
2,191 citations
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...However, MRAM has other advantages such as potentially infinite endurance (against ~10(5) cycles for a Flash) and potential for sub-ns operation [66, 73, 74], that makes it competitive as “universal” memory....
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...A realistic treatment of the effect [65] includes both quantum effects at the interfaces (spin dependent transmission of Bloch states) and diffusive transport theory (spin accumulation effects), while the dynamical behaviour can be studied through a modified Landau-LifshitzGilbert equation describing the damped precession of magnetization in the presence of spin transfer torque and thermal excitations [65, 66]....
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TL;DR: In this paper, the authors demonstrate a technique that allows direct electrical measurements of microwave-frequency dynamics in individual nanomagnets, propelled by a d.c. spin-polarized current.
Abstract: The recent discovery that a spin-polarized electrical current can apply a large torque to a ferromagnet, through direct transfer of spin angular momentum, offers the possibility of manipulating magnetic-device elements without applying cumbersome magnetic fields. However, a central question remains unresolved: what type of magnetic motions can be generated by this torque? Theory predicts that spin transfer may be able to drive a nanomagnet into types of oscillatory magnetic modes not attainable with magnetic fields alone, but existing measurement techniques have provided only indirect evidence for dynamical states. The nature of the possible motions has not been determined. Here we demonstrate a technique that allows direct electrical measurements of microwave-frequency dynamics in individual nanomagnets, propelled by a d.c. spin-polarized current. We show that spin transfer can produce several different types of magnetic excitation. Although there is no mechanical motion, a simple magnetic-multilayer structure acts like a nanoscale motor; it converts energy from a d.c. electrical current into high-frequency magnetic rotations that might be applied in new devices including microwave sources and resonators.
1,869 citations
TL;DR: In this paper, the physics of spin transfer torque in magnetic devices are discussed and an elementary discussion of the mechanism and experimental progress in this field is provided, along with a review of theoretical and experimental results.
1,688 citations