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Magnetotoroidic Effect

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Physicists discover 'magnetotoroidic effect

September 26, 2011 by Lisa Zyga (PhysOrg.com)

—For many years, scientists have known about the magnetoelectric effect, in which an electric field can induce and control a magnetic field, and vice versa. In this effect, the electric field has always been homogeneous. Now, scientists have found that a curled electric field can also be used to control magnetic fields, constituting a novel phenomenon that they call the "magnetotoroidic effect." “A homogeneous electric field is one in which the electric field is a constant everywhere, as that produced by opposite static charges on two metallic capacitor plates,” Wei Ren of the University of Arkansas told PhysOrg.com. “On the other hand, a time-varying magnetic field can also induce an electric field that possesses a curl according to the Maxwell-Faraday equation. However, such a curl is zero in the homogeneous electric field.”

Read more at: http://phys.org/news/2011-09-physicists-magnetotoroidic-effect.html#jCp

APS » Journals » Phys. Rev. Lett. » Volume 107 » Issue 12
Phys. Rev. Lett. 107, 127202 (2011) [5 pages]

Prediction of the Magnetotoroidic Effect from Atomistic Simulations

Wei Ren and L. Bellaiche
Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA
Received 24 February 2011; published 12 September 2011

Abstract

An effective Hamiltonian technique is used to investigate the effect of applying curled electric fields on physical properties of stress-free BiFeO3 dots being under open-circuit electrical boundary conditions. It is discovered that such fields can lead to a control of not only the magnitude but also the direction of the magnetization. Such control originates from the field-induced transformation or switching of electrical vortices and their couplings with oxygen octahedral tilts and magnetic dipoles. This control involves striking intermediate states and constitutes a novel phenomenon that can be termed a “magnetotoroidic” effect.
© 2011 American Physical Society
URL: http://link.aps.org/doi/10.1103/PhysRevLett.107.127202
DOI: 10.1103/PhysRevLett.107.127202