Eur. Phys. J. E (2017) 40: 28
https://doi.org/10.1140/epje/i2017-11516-6

Regular Article

Action of fields on captive disclination loops

¹ Laboratoire de Physique des Solides, Université Paris-Sud, Bât. 510, 91405, Orsay, France
² École normale supérieure de Cachan, 61 Avenue du Président Wilson, 94235, Cachan, France
³ CENIMAT, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829 - 516, Caparica, Portugal
⁴ Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000, Ljubljana, Slovenia

^* e-mail: pawel.pieranski@u-psud.fr

Received: 7 December 2016
Accepted: 22 February 2017
Published online: 20 March 2017

Abstract

We report on two effects observed in experiments with captive disclination loops on polymeric fibers immersed in nematics and submitted to electric and/or magnetic fields. We show that the magnetic field oblique to a fiber with axial or helicoidal anchoring on its surface induces translation of disclination loops. Fields orthogonal to fibers with helicoidal anchoring make disclination loops rotate around the field direction. In the linear regime of this last chirogyral effect, the angle of rotation is proportional to the helix wave vector and its sense unveils the chirality of the helix. We propose a model explaining the origin and all features of these two effects.