Eur. Phys. J. B 12, 261-268 (1999)
https://doi.org/10.1007/s100510051003

Phase diagram of magnetic polymers

¹ Service de Physique Théorique, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
² Istituto Nazionale per la Fisica della Materia (INFM) and Dipartimento di Fisica dell'Universita' di Padova, via Marzolo 8, 35131 Padova, Italy

Corresponding author: ^a orland@spht.saclay.cea.fr

Received: 11 February 1999
Published online: 15 November 1999

Abstract

We consider polymers made of magnetic monomers (Ising or Heisenberg-like) in a good solvent. These polymers are modeled as self-avoiding walks on a cubic lattice, and the ferromagnetic interaction between the spins carried by the monomers is short-ranged in space. At low temperature, these polymers undergo a magnetic induced first order collapse transition, that we study at the mean field level. Contrasting with an ordinary Θ point, there is a strong jump in the polymer density, as well as in its magnetization. In the presence of a magnetic field, the collapse temperature increases, while the discontinuities decrease. Beyond a multicritical point, the transition becomes second order and Θ-like. Monte Carlo simulations for the Ising case are in qualitative agreement with these results.