Eur. Phys. J. B 24, 387-394 (2001)
https://doi.org/10.1007/s10051-001-8688-z

Steps and facets at the surface of soft crystals

¹ Laboratoire d'Étude des Propriétés Électroniques des Solides CNRS, BP 166, 38042 Grenoble Cedex 9, France
² European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex 9, France
³ Laboratoire de Physique Statistique de l'École Normale Supérieure associé aux Universités Paris 6 et Paris 7 et au CNRS, 24 rue Lhomond, 75231 Paris Cedex 05, France

Corresponding author: ^a Fabio.Pistolesi@polycnrs-gre.fr

Received: 25 June 2001
Published online: 15 December 2001

Abstract

We consider the shape of crystals which are soft in the sense that their elastic modulus μ is small compared to their surface tension γ, more precisely where a is the lattice spacing. We show that their surface steps penetrate inside the crystal as edge dislocations. As a consequence, these steps are broad with a small energy which we calculate. We also calculate the elastic interaction between steps a distance d apart, which is a repulsion. We finally calculate the roughening temperatures of successive facets in order to compare with the remarkable shapes of lyotropic crystals recently observed by Pieranski et al. [CITE]. Good agreement is found.