Chirality tunneling in mesoscopic antiferromagnetic domain walls

We studied the quantum dynamics of ferromagnetic domain walls (topological kink-type solitons) in one dimensional ferromagnetic spin chains. We show that the tunneling probability does not depend on the number of spins in a domain wall; thus, this probability can be large even for a domain wall containing a large number of spins. We also predict that there is a strong interplay between the tunneling of a wall from one lattice site to another (tunneling of the kink coordinate) and the tunneling of the kink topological charge (so-called chirality). Both of these elementary processes are suppressed for kinks in one-dimensional ferromagnets with half-integer spin. The dispersion law (i.e., the domain wall energy versus momentum) is essentially different for chains with either integer or half-integer spins. The predicted quantum effects could be observed for mesoscopic magnetic structures, e.g., chains of magnetic clusters, large-spin molecules, or nanosize magnetic dots.

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“…see Eqs. (18) or (19). The most crucial point is the presence of the double periodicity of H(P, X), with respect to both X and P .…”

Section: Quantum Tunneling Effects In Kink Dynamicsmentioning

confidence: 99%

“…For kinks in antiferromagnets, chirality tunneling is not correlated with the translational motion of kinks. 17,18 In contrast, some results known in the literature imply that for ferromagnets the situation can be different. Ref.…”

Section: Introductionmentioning

confidence: 99%

Chirality tunneling and quantum dynamics for domain walls in mesoscopic ferromagnets

et al. 2008

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“…Although quantum tunneling in the context of field theory, for instance the tunneling of domain walls [8][9][10][11][12][13][14][15][16][17][18], has been investigated, the explicit, multidimensional (time-space) instanton configurations have not been studied extensively. In almost all the literature, a collective coordinate of the domain wall is introduced to describe the behavior of quantum tunneling, or the situation is simplified to the case of a uniform spin configuration, namely, single domain magnetic grain.…”

Section: Introductionmentioning

confidence: 99%

Macroscopic Quantum Coherence of an Antiferromagnetic Spin Chain with Biaxial Anisotropy in an External Magnetic Field

Zheng

Zhao

2010

Int J Theor Phys

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We in this paper provide a sine-Gordon model of (1 + 1)-dimensions in which macroscopic quantum coherence of domain walls may be observed. The tunneling amplitude in field models of (1 + 1)-dimensions, such as sine-Gordon, is negligible small at zero temperature. In the long, but finite-length chain at finite temperature it is possible to have a finite, but still very small one. In the present model of the antiferromagnetic spin chain with biaxial anisotropy in an external magnetic field, in which the height of the sine-Gordon barrier can be tuned, the tunneling amplitude is shown to be enhanced by adjusting the external parameter.

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“…Among others, a magnetic domain wall has attracted much attention both theoretically and experimentally, because it is expected to exhibit macroscopic quantum phenomena [4][5][6][7][8][9][10][11]. As a theoretical technique to evaluate the quantum dynamics of the domain wall, the spin coherent state path integral in the continuous-time formalism [12] is frequently used.…”

Section: Introductionmentioning

confidence: 99%

Method of collective degrees of freedom in spin-coherent-state path integral

Shibata

Takagi

2001

Phys. Atom. Nuclei

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We present a detailed field theoretic description of those collective degrees of freedom (CDF) which are relevant to study macroscopic quantum dynamics of a quasi-one-dimensional ferromagnetic domain wall. We apply spin coherent state path integral (SCSPI) in the proper discrete time formalism (a) to extract the relevant CDF's, namely, the center position and the chirality of the domain wall, which originate from the translation and the rotation invariances of the system in question, and (b) to derive effective action for the CDF's by elimination of environmental zero-modes with the help of the Faddeev-Popov technique. The resulting effective action turns out to be such that both the center position and the chirality can be formally described by boson coherent state path integral. However, this is only formal; there is a subtle departure from the latter.

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Chirality tunneling in mesoscopic antiferromagnetic domain walls

Cited by 20 publications

References 18 publications

Chirality tunneling and quantum dynamics for domain walls in mesoscopic ferromagnets

Chirality tunneling and quantum dynamics for domain walls in mesoscopic ferromagnets

Macroscopic Quantum Coherence of an Antiferromagnetic Spin Chain with Biaxial Anisotropy in an External Magnetic Field

Method of collective degrees of freedom in spin-coherent-state path integral

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