scholarly journals Symmetry breaking in spin spirals and skyrmions by in-plane and canted magnetic fields

2016 ◽  
Vol 18 (7) ◽  
pp. 075007 ◽  
Author(s):  
L Schmidt ◽  
J Hagemeister ◽  
P-J Hsu ◽  
A Kubetzka ◽  
K von Bergmann ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Symmetry Breaking

scholarly journals DYNAMICAL SYMMETRY BREAKING IN THE EXTERNAL GRAVITATIONAL AND CONSTANT MAGNETIC FIELDS

1999 ◽  
Vol 14 (04) ◽  
pp. 481-503 ◽  
Author(s):  
T. INAGAKI ◽  
S. D. ODINTSOV ◽  
YU. I. SHIL'NOV
Keyword(s):  
Magnetic Field ◽  
Gravitational Field ◽  
Magnetic Fields ◽  
Symmetry Breaking ◽  
Effective Potential ◽  
Constant Magnetic Field ◽  
Dynamical Symmetry ◽  
Green Functions ◽  
Dynamical Symmetry Breaking ◽  
Njl Model

We investigate the effects of the external gravitational and constant magnetic fields to the dynamical symmetry breaking. As simple models of the dynamical symmetry breaking we consider the Nambu–Jona-Lasinio (NJL) model and the supersymmetric Nambu–Jona-Lasinio (SUSY NJL) model nonminimally interacting with the external gravitational field and minimally interacting with constant magnetic field. The explicit expressions for the scalar and spinor Green functions are found to the first order in the space–time curvature and exactly for a constant magnetic field. We obtain the effective potential of the above models from the Green functions in the magnetic field in curved space–time. Calculating the effective potential numerically with the varying curvature and/or magnetic fields we show the effects of the external gravitational and magnetic fields to the phase structure of the theories. In particular, increase of the curvature in the spontaneously broken phase of the chiral symmetry due to the fixed magnetic field makes this phase to be less broken. At the same time the strong magnetic field quickly induces chiral symmetry breaking even in the presence of fixed gravitational field within the nonbroken phase.

scholarly journals Direct observation of photonic Landau levels and helical edge states in strained honeycomb lattices

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Omar Jamadi ◽  
Elena Rozas ◽  
Grazia Salerno ◽  
Marijana Milićević ◽  
Tomoki Ozawa ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Symmetry Breaking ◽  
Distinctive Feature ◽  
Direct Evidence ◽  
Landau Levels ◽  
Honeycomb Lattice ◽  
Edge States ◽  
Photonic Lattices ◽  
Synthetic Magnetic Field

Abstract We report the realization of a synthetic magnetic field for photons and polaritons in a honeycomb lattice of coupled semiconductor micropillars. A strong synthetic field is induced in both the s and p orbital bands by engineering a uniaxial hopping gradient in the lattice, giving rise to the formation of Landau levels at the Dirac points. We provide direct evidence of the sublattice symmetry breaking of the lowest-order Landau level wavefunction, a distinctive feature of synthetic magnetic fields. Our realization implements helical edge states in the gap between n = 0 and n = ±1 Landau levels, experimentally demonstrating a novel way of engineering propagating edge states in photonic lattices. In light of recent advances in the enhancement of polariton–polariton nonlinearities, the Landau levels reported here are promising for the study of the interplay between pseudomagnetism and interactions in a photonic system.

Torque density measurements on vortex fluids produced by symmetry-breaking rational magnetic fields

Soft Matter ◽  
2014 ◽  
Vol 10 (33) ◽  
pp. 6139-6146 ◽  
Author(s):  
Kyle J. Solis ◽  
James E. Martin
Keyword(s):  
Magnetic Fields ◽  
Symmetry Breaking ◽  
Magnetic Particle ◽  
Infinite Family ◽  
Particle Suspensions ◽  
Density Measurements ◽  
Torque Density ◽  
Strong Vorticity

A recently-discovered infinite family of symmetry-breaking rational magnetic fields creates “vortex fluids” that produce strong vorticity along any axis in magnetic particle suspensions.

scholarly journals SPIN POLARIZATION BY EXTERNAL MAGNETIC FIELDS, AHARONOV-BOHM FLUX STRINGS, AND CHIRAL SYMMETRY BREAKING IN QED3

1996 ◽  
Vol 11 (10) ◽  
pp. 1715-1731 ◽  
Author(s):  
RAJESH R. PARWANI
Keyword(s):  
Magnetic Fields ◽  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
Three Dimensional ◽  
Index Theorem ◽  
Flux Tubes ◽  
Four Dimensions ◽  
General Index ◽  
Aharonov Bohm

In the first part, the induced vacuum spin around an Aharonov-Bohm flux string in massless three-dimensional QED is computed explicitly and the result is shown to agree with a general index theorem. A previous observation in the literature, that the presence of induced vacuum quantum numbers which are not periodic in the flux make an integral-flux AB string visible, is reinforced. In the second part, a recent discussion of chiral symmetry breaking by external magnetic fields in parity-invariant QED 3 and its relation to the induced spin in parity-noninvariant QED 3 is further elaborated. Finally, other vacuum polarization effects around flux tubes in different variants of QED, in three and four dimensions are mentioned.

scholarly journals Actuation of magnetoelastic membranes in precessing magnetic fields

2019 ◽  
Vol 116 (7) ◽  
pp. 2500-2505 ◽  
Author(s):  
Chase Austyn Brisbois ◽  
Mykola Tasinkevych ◽  
Pablo Vázquez-Montejo ◽  
Monica Olvera de la Cruz
Keyword(s):  
Molecular Dynamics ◽  
Magnetic Fields ◽  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Continuum Mechanics ◽  
Superparamagnetic Nanoparticles ◽  
Magnetic Interactions ◽  
Robotic Systems ◽  
Elastic Media ◽  
Dynamics Simulations

Superparamagnetic nanoparticles incorporated into elastic media offer the possibility of creating actuators driven by external fields in a multitude of environments. Here, magnetoelastic membranes are studied through a combination of continuum mechanics and molecular dynamics simulations. We show how induced magnetic interactions affect the buckling and the configuration of magnetoelastic membranes in rapidly precessing magnetic fields. The field, in competition with the bending and stretching of the membrane, transmits forces and torques that drives the membrane to expand, contract, or twist. We identify critical field values that induce spontaneous symmetry breaking as well as field regimes where multiple membrane configurations may be observed. Our insights into buckling mechanisms provide the bases to develop soft, autonomous robotic systems that can be used at micro- and macroscopic length scales.

scholarly journals Symmetry Breaking in the Solar Dynamo: Nonlinear Solutions

1990 ◽  
Vol 138 ◽  
pp. 355-358
Author(s):  
R.L. Jennings ◽  
N.O. Weiss
Keyword(s):  
Magnetic Fields ◽  
Symmetry Breaking ◽  
Spatial Structure ◽  
Periodic Solutions ◽  
Mixed Mode ◽  
Dynamo Model ◽  
The Sun ◽  
Bifurcation Structure ◽  
Secondary Bifurcations ◽  
Nonlinear Solutions

We examine an idealized αω-dynamo model in which the magnetic fields depend only on latitude and time. The solutions that bifurcate from the field-free state are either symmetric or antisymmetric about the equator (quadrupolar or dipolar respectively). Nonlinear steady and periodic solutions, whether stable or unstable, can be followed numerically as the dynamo number is varied, revealing a rich bifurcation structure with mixed-mode solutions (lacking symmetry about the equator) appearing at secondary bifurcations. These results show how stable asymmetric fields can occur in the sun and illustrate the formation of complicated spatial structure in more active stars.

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