title: Magnetic-field-induced changes of the isotropic-nematic phase transition in side-chain polymer liquid crystals.
abstract: The isotropic-nematic (I-N) phase transition of side-chain polymer liquid crystals is intrinsically a weak first-order transition with a biphasic region spread over a wide temperature interval. In the presence of high magnetic fields we find the I-N transition to become a strong first order. The I-N biphasic region shrinks its temperature window as larger magnetic fields are applied, until it completely disappears and the transition completes at a fixed temperature. We interpret this behavior as a consequence of the nonlinear coupling of the magnetic field to the system free energy, via the suppression of the order fluctuations in the nematic mesophase at the I-N transition crossing.
authors.affiliation: Research Institute for Materials, High Field Magnet Laboratory, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands. boamfa@sci.kun.nl
authors.forename: M I
authors.initials: MI
authors.lastname: Boamfa
authors.forename: K
authors.initials: K
authors.lastname: Viertler
authors.forename: A
authors.initials: A
authors.lastname: Wewerka
authors.forename: F
authors.initials: F
authors.lastname: Stelzer
authors.forename: P C M
authors.initials: PC
authors.lastname: Christianen
authors.forename: J C
authors.initials: JC
authors.lastname: Maan