title: Measurement of elastic forces between iron colloidal particles in a nematic liquid crystal.
abstract: The forces that arise between two iron particles in a nematic liquid crystal with a strong homeotropic anchoring were studied. For the first time, the short range repulsive force resulting from the presence of a hedgehog defect between two particles was precisely determined thanks to application of a small magnetic field and observation of the equilibrium position resulting from the balance between the elastic and magnetic forces. Above a given threshold force, the particles stuck together whereas the hedgehog defect was expelled and transformed into a Saturn ring located between the particles. The attractive part of the interparticle force was determined with the same method on the entire range of separation distances; we found that the equilibrium distance between two particles was r = 1.19 +/- 0.05 <d> (<d> was the average diameter of the pair of particles).
authors.affiliation: Laboratoire de Physique de la Matière Condensée (UMR6622), Université de Nice Sophia-Antipolis, Parc Valrose 06108 Nice Cedex 2, France.
authors.forename: C M
authors.initials: CM
authors.lastname: Noël
authors.forename: G
authors.initials: G
authors.lastname: Bossis
authors.forename: A-M
authors.initials: AM
authors.lastname: Chaze
authors.forename: F
authors.initials: F
authors.lastname: Giulieri
authors.forename: S
authors.initials: S
authors.lastname: Lacis
mesh_terms: D003102:Colloids / Q000032:analysis / Q000737:chemistry*; D003198:Computer Simulation; D004548:Elasticity; D004574:Electromagnetic Fields; D007501:Iron / Q000032:analysis / Q000737:chemistry*; D050866:Liquid Crystals / Q000032:analysis / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D049329:Nanostructures / Q000032:analysis / Q000737:chemistry*; D010316:Particle Size; D013314:Stress, Mechanical
chemical_list: D003102:Colloids; D007501:Iron