Kamilla Faizullina | Searcharxiv

arXiv2024

XY model on a self-avoiding walk

We study a lattice model of a magnetic polymer where the XY spin variables are located on a self-avoiding walk (SAW) on a regular lattice in two and three dimensions. We consider the regime where both spins and conformations are dynamic, thus the XY model is defined on a dynamic lattice and conformations generate an annealed disorder. Using Monte Carlo simulations, we characterize the globule-coil and ferromagnetic phase transitions, and pay special attention to the vicinity of the theta-point. Our numerical results suggest that the transitions are continuous in two dimensions and first-order in three dimensions, which is similar to related models with Ising spins.

cond-mat.stat-mech↗

arXiv2021

Critical and geometric properties of magnetic polymers across the globule-coil transition

We study a lattice model of a single magnetic polymer chain, where Ising spins are located on the sites of a lattice self-avoiding walk in $d=2$. We consider the regime where both conformations and magnetic degrees of freedom are dynamic, thus the Ising model is defined on a dynamic lattice and conformations generate an annealed disorder. Using Monte Carlo simulations, we characterize the globule-coil and ferromaget-to-paramagnet transitions, which occur simultaneously at a critical value of the spin-spin coupling. We argue that the transition is continuous - in contrast to $d=3$ where it is first-order. Our results suggest that at the transition the metric exponent takes the theta-polymer value $ν=4/7$ but the crossover exponent $ϕ\approx 0.7$, which differs from the expected value for a $θ$-polymer.

cond-mat.stat-mech↗