Macroscopic coherent tunneling in a small particle of an uncompensated antiferromagnet in a strong magnetic field

Иванов, Б. А.; Kireev, V. E.

doi:10.1134/1.568041

Cited by 7 publications

(13 citation statements)

References 7 publications

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“…II A]. In contrast, h x ≫ |δs|8J/N guarantees that there are two energetically degenerate, macroscopically distinct spin configurations between which spin tunneling may take place 25 and hence, in general, will shift the range of magnetic fields in which a tunneling scenario as discussed in the present context [ Fig. 1] is valid.…”

Section: A Phenomenological Model For the Modified Fwmentioning

confidence: 83%

“…Henceforth, we will always assume that B x is large enough to satisfy Eq. (25). For sufficiently large k z , the two-state model for the low energy sector of the system outlined in Sec.…”

Section: A Phenomenological Model For the Modified Fwmentioning

confidence: 99%

“…In the range of validity of our theory [Eq. (25)], for δs = 0 [Figs. 6,8], the agreement of ED (⋄) with analytic results (-) is both qualitatively and quantitatively convincing.…”

Section: Dynamics Of the Modified Fwmentioning

confidence: 99%

“…47,48,6 A drawback of the setup considered in Ref. 25 is that, for uniaxial hard axis anisotropy, spin tunneling leaves the total spin S invariant if B is applied perpendicular to the hard axis. As for the FW with equal sublattice spins, spin tunneling cannot be observed in AC susceptibility measurements.…”

Section: Spin Quantum Tunneling In Ferritinmentioning

confidence: 99%

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Thermodynamics and spin-tunneling dynamics in ferric wheels with excess spin

Meier

Loss

2001

Phys. Rev. B

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We study theoretically the thermodynamic properties and spin dynamics of a class of magnetic rings closely related to ferric wheels, antiferromagnetic ring systems, in which one of the Fe (III) ions has been replaced by a dopant ion to create an excess spin. Using a coherent-state spin path integral formalism, we derive an effective action for the system in the presence of a magnetic field. We calculate the functional dependence of the magnetization and tunnel splitting on the magnetic field and show that the parameters of the spin Hamiltonian can be inferred from the magnetization curve. We study the spin dynamics in these systems and show that quantum tunneling of the Néel vector also results in tunneling of the total magnetization. Hence, the spin correlation function shows a signature of Néel vector tunneling, and electron spin resonance (ESR) techniques or AC susceptibility measurements can be used to measure both the tunneling and the decoherence rate. We compare our results with exact diagonalization studies on small ring systems. Our results can be easily generalized to a wide class of nanomagnets, such as ferritin. 75.50.Xx,75.10.Jm,03.65.Sq,73.40.

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Section: A Phenomenological Model For the Modified Fwmentioning

confidence: 83%

“…Henceforth, we will always assume that B x is large enough to satisfy Eq. (25). For sufficiently large k z , the two-state model for the low energy sector of the system outlined in Sec.…”

Section: A Phenomenological Model For the Modified Fwmentioning

confidence: 99%

“…In the range of validity of our theory [Eq. (25)], for δs = 0 [Figs. 6,8], the agreement of ED (⋄) with analytic results (-) is both qualitatively and quantitatively convincing.…”

Section: Dynamics Of the Modified Fwmentioning

confidence: 99%

Section: Spin Quantum Tunneling In Ferritinmentioning

confidence: 99%

See 2 more Smart Citations

Thermodynamics and spin-tunneling dynamics in ferric wheels with excess spin

Meier

Loss

2001

Phys. Rev. B

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“…The presence of a magnetic field may also lead to similar effects; this was noted in the analysis of the nonlinear dynamics of antiferromagnets 22 as well as for the MQT effect, see Ref. 22 and recent publications 5,[23][24][25][26][27] .…”

Section: Introductionmentioning

confidence: 73%

Interference of instanton trajectories during quantum tunneling in small particles of real antiferromagnets

Иванов

Kireev

2002

J. Exp. Theor. Phys.

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For a two-sublattice antiferromagnet the Lagrangian is constructed taking into account Berry phase whose form is matched with the quantum-mechanical Heisenberg Hamiltonian. Tunnel effects are analyzed taking into account the crystallographic symmetry and possible types of Dzyaloshinskii-Moriya interaction. It is shown that, when the real magnetic symmetry and the Dzyaloshinskii-Moriya interaction are taken into consideration, the effects of a destructive instanton interference and the suppression of macroscopic quantum tunneling can play an essential role. It also may lead to a periodic dependence of the ground-state level splitting on the Dzyaloshinskii-Moriya interaction constant; the magnitude of this splitting is calculated.

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Mesoscopic antiferromagnets: statics, dynamics, and quantum tunneling (Review)

Иванов

2005

Low Temperature Physics

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The static and dynamic, quantum and classical properties of antiferromagnets (AFMs) are discussed from a unified point of view. Attention is directed mainly toward mesoscopic magnets, i.e., materials with characteristic scales of nonuniformities of the order of atomic dimensions. The creation of such materials and their study and application have largely shaped the face of the physics of our day. This class includes small magnetic particles and their arrays, magnetic superlattices and clusters, and high-spin molecules. The traditional problems of the physics of antiferromagnetism are also discussed (symmetry analysis of AFMs, reorientation transitions, equations of spin dynamics), but they are represented only to the extent that it is useful to do so for subsequent consideration of the quantum and classical properties of mesoscopic AFMs. For description of the spin dynamics of AFMs, a magnetic Lagrangian of a form matched with the quantum-mechanical Hamiltonian is constructed. The lowering of the symmetry of the AFMs, both that due to conventional causes such as an external magnetic field and that due to the partial decompensation of the sublattice spins, is taken into account. The latter effect is especially important for mesoscopic particles of AFMs of the ferrite type. The influence of defects and of the surface on the reorientation transitions in AFMs is discussed in detail. These effects, which are of fundamental importance for the description of small particles of AFMs, are observed for magnetic superlattices with an antiferromagnetic interaction of the elements of the superlattices. The description of macroscopic quantum effects in mesoscopic AFMs plays a prominent role. The spin Lagrangian obtained describes new tunneling effects such as an oscillatory dependence of the tunneling probability on magnetic field. Quantum effects in magnetic systems with a nonuniform ground state are investigated. These effects can be described as the change due to processes of tunneling of the topological charges of various natures that characterize these states.

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Macroscopic coherent tunneling in a small particle of an uncompensated antiferromagnet in a strong magnetic field

Cited by 7 publications

References 7 publications

Thermodynamics and spin-tunneling dynamics in ferric wheels with excess spin

Thermodynamics and spin-tunneling dynamics in ferric wheels with excess spin

Interference of instanton trajectories during quantum tunneling in small particles of real antiferromagnets

Mesoscopic antiferromagnets: statics, dynamics, and quantum tunneling (Review)

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