Quantum phase and persistent magnetic moment current and Aharonov-Casher effect in a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>s</mml:mi><mml:mo>=</mml:mo></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mfrac><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:mfrac></mml:math>mesoscopic ferromagnetic ring

Cao, Zhong; Yu, Xueping; Han, Rushan

doi:10.1103/physrevb.56.5077

Cited by 28 publications

(23 citation statements)

References 26 publications

(20 reference statements)

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“…In fact, this is an example of different topological effects in quantum mechanics: an extra topological phase is acquired by the quantum orbital motion of neutral magnetic moments in mesoscopic rings in the electric field. Particularly, in a ferromagnet, spin waves that propagate in the applied electric field acquire an additional quantum phase, the so-called Aharanov-Casher phase [5,6]. Microscopically this effect originates from the spin-orbit interaction.…”

Section: Introductionmentioning

confidence: 99%

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Electric-field control of spin-wave power flow and caustics in thin magnetic films

2018

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An external electric field can modify the strength of the spin-orbit interaction between spins of ions in magnetic crystals. This influence leads to a spin-wave frequency shift that is linear in both the applied electric field and the wave vector of the spin wave. Here we study theoretically the external electric field as a means of control of the spin-wave power flow in thin ferromagnets. The spin-wave group velocity and focusing patterns are obtained from the slowness (isofrequency) curves by evaluating their curvature at each point of the reciprocal space. We show that the combination of the magnetodipole interaction and the electric field can result in nonreciprocal unidirectional caustic beams of dipole-exchange spin waves. We demonstrate that the degree of asymmetry of the spin-wave power flow can be tuned with the external electric field. Our findings open a novel avenue for spin-wave manipulation and development of electrically tunable magnonic devices.

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Section: Introductionmentioning

confidence: 99%

“…Originally, the frequency shift was expected to be small (∼0.01%) [6]. However, subsequent microscopic calculations based on the superexchange model pointed out that the electric-field effect could be sufficiently large to be used to control efficiently spin currents [2,3].…”

Section: Introductionmentioning

confidence: 99%

Electric-field control of spin-wave power flow and caustics in thin magnetic films

2018

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“…Note that in the presence of spin-orbit coupling spin currents in spin chains can also be driven by inhomogeneous electric fields [8], due to the Aharonov-Casher effect [9]. As detailed later on, the magnetization current is carried by magnons and endows the ring with an electric dipole field, which is the counterpart of the magnetic dipole field associated with the persistent charge current in a normal metal ring.…”

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confidence: 99%

Persistent Spin Currents in Mesoscopic Heisenberg Rings

2003

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We show that at low temperatures T an inhomogeneous radial magnetic field with magnitude B gives rise to a persistent magnetization current around a mesoscopic ferromagnetic Heisenberg ring. Under optimal conditions this spin current can be as large as gµB(T / ) exp 1/2 ], as obtained from leading-order spin-wave theory. Here g is the gyromagnetic factor, µB is the Bohr magneton, and ∆ is the energy gap between the ground state and the first spin-wave excitation. The magnetization current endows the ring with an electric dipole moment.PACS numbers: 75.10. Jm, 75.10.Pq, 75.30.Ds, 73.23.Ra The controlled fabrication of submicron devices has opened the door to a rich new field of theoretical and experimental physics. At low temperatures these devices are mesoscopic in the sense that their quantum states must be described by coherent wave functions extending over the entire system. Then the usual assumptions underlying the averaging procedure in statistical mechanics are not necessarily valid, and quantum-mechanical interference effects become important [1].A prominent example is persistent currents in mesoscopic normal metal rings threaded by a magnetic flux [1]. Although this phenomenon was predicted long ago [2,3], the experimental difficulties in measuring persistent currents in an Aharonov-Bohm geometry were only overcome in the past decade [4,5,6]. Surprisingly, for metallic rings in the diffusive regime the observed currents were much larger than predicted by theory [1]. On the other hand, in the ballistic regime [6] the order of magnitude of the observed current can be explained with a simple model of free fermions moving on a ring pierced by a magnetic flux φ. Then the stationary en-. ., are the allowed wavevectors for a ring with circumference L. Here φ 0 = hc/e is the flux quantum and m * is the effective mass of the electrons. In the simplest approximation, one may calculate the current I = −c∂Ω gc (φ)/∂φ at constant chemical potential µ from the flux-dependent part of the grand canonical potential Ω gc (φ). At finite temperature T , one obtains for spinless fermionswhere v n = k n /m * . For T ≪ µ the amplitude of the current is I max ≈ −ev F /L (where v F is the Fermi velocity), in agreement with experiment [6].In this Letter, we show that Heisenberg spin chains in inhomogeneous magnetic fields can be used to realize a spin current analogue of mesoscopic persistent currents in normal metal rings. Note that in the presence of spin-orbit coupling spin currents in spin chains can also be driven by inhomogeneous electric fields [8], due to the Aharonov-Casher effect [9]. As detailed later on, the magnetization current is carried by magnons and endows the ring with an electric dipole field, which is the counterpart of the magnetic dipole field associated with the persistent charge current in a normal metal ring. We find that for realistic parameters the spin analogues of the experiments in Refs. 4, 5, 6 require the detection of a potential drop on the order of nanovolts.Due to its relevance for informat...

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“…More sophisticated mechanisms exploited the Berry phase accumulated by spin waves that propagate on a non-collinear magnetic texture [4,11]. In a parallel development, Cao et al [12] studied the effect on spin waves of an electric field-induced Aharonov-Casher (AC) phase [13]. More recently, the influence of electric fields on spin waves has been studied both theoretically [14] and experimentally [15] and a strong shift of spin-wave dispersion induced by an electric field has been reported [15].…”

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confidence: 99%

Electric Control of Spin Currents and Spin-Wave Logic

2011

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Spin waves in insulating magnets are ideal carriers for spin currents with low energy dissipation. An electric field can modify the dispersion of spin waves, by directly affecting, via spin-orbit coupling, the electrons that mediate the interaction between magnetic ions. Our microscopic calculations based on the super-exchange model indicate that this effect of the electric field is sufficiently large to be used to effectively control spin currents. We apply these findings to the design of a spinwave interferometric device, which acts as a logic inverter and can be used as a building block for room-temperature, low-dissipation logic circuits.One of the major challenges of contemporary electronics is to reduce dissipation as the size of devices shrinks to the nanometric scale. In this context, spin-wave spintronics, so called magnonics, with insulating magnets offers interesting possibilities [1,2]. While in metals and semiconductors the spin current is carried by mobile conduction electrons/holes, which inevitably dissipate energy as they move, in a magnetic insulator, such as Y 3 F e 5 O 12 (YIG), the spin current is carried by a collective motion of magnetic moments -a spin wave -with no charge displaced. The spin current propagating in these insulating material is thus totally free of energy dissipation from Joule heating, and almost free of dissipation from other sources (e.g. electron-magnon scattering): the coherence length can be as large as several centimeters [2]. For these reasons, magnetic insulators have attracted considerable attention in recent theoretical [3][4][5] and experimental [2, 6] work. For example, Kajiwara et al. [2], have demonstrated injection and extraction of spin waves into and out of a YIG wave guide [8]. Kostylev et al. [9], have designed an ingenious scheme of spin-wave logic, based on the interference between spin waves traveling along different arms of a Mach-Zehnder interferometer (a schematic illustration of a Mach-Zehnder spin wave interferometer is shown in Fig. 1).A crucial element of magnonics [1] is the phase shifter -a device that changes the phase of propagating spin waves. Several mechanisms have been proposed in the past to implement controlled phase shifts on spin waves. The simplest and most direct, is the application of a magnetic field, which shifts the dispersion [10], thus changing the wave vector at constant frequency [9]. More sophisticated mechanisms exploited the Berry phase accumulated by spin waves that propagate on a non-collinear magnetic texture [4,11]. In a parallel development, Cao et al.[12] studied the effect on spin waves of an electric field-induced Aharonov-Casher (AC) phase [13]. More recently, the influence of electric fields on spin waves has been studied both theoretically [14] and experimentally [15] and a strong shift of spin-wave dispersion induced by an electric field has been reported [15].In this Letter we directly tackle the problem of controlling the phase of a spin wave (and hence the spin Figure 1. A Mach-Zehnder spin-wave interfer...

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Quantum phase and persistent magnetic moment current and Aharonov-Casher effect in as=12mesoscopic ferromagnetic ring

Cited by 28 publications

References 26 publications

Electric-field control of spin-wave power flow and caustics in thin magnetic films

Electric-field control of spin-wave power flow and caustics in thin magnetic films

Persistent Spin Currents in Mesoscopic Heisenberg Rings

Electric Control of Spin Currents and Spin-Wave Logic

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