Field-induced phase transitions in ferro-antiferromagnetic diblock copolymers

Fuente: arXiv
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Hauptverfasser: Raiola, Alberto, Locatelli, Emanuele, Marenduzzo, Davide, Orlandini, Enzo
Format: Preprint
Veröffentlicht: 2026
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author Raiola, Alberto
Locatelli, Emanuele
Marenduzzo, Davide
Orlandini, Enzo
author_facet Raiola, Alberto
Locatelli, Emanuele
Marenduzzo, Davide
Orlandini, Enzo
contents We study the equilibrium properties of a model of magnetic diblock copolymer where each monomer is decorated with an Ising-like spin. Spins interact ferromagnetically within each block and antiferromagnetically across blocks, generating frustration between magnetic ordering and spatial organization. By employing a mean-field approach and Monte Carlo simulations for self-avoiding walks on the cubic lattice, we investigate the system's response to an external magnetic field. We discover a rich phase diagram that includes: a swollen phase with both filaments magnetically disordered and spatially extended; a mixed compact phase characterized by a single globule in which the two filaments are strongly intertwined; a segregated compact phase composed of two globular, magnetically ordered, and spatially separated blocks. Further, if the magnitude of the intra-block ferromagnetic interaction differs between the two blocks, we observe a hybrid segregated (``tadpole'') phase where one extended block coexists with a collapsed one. Mean-field predictions are in quantitative agreement with Monte Carlo results for the location of the phase boundaries. These findings provide a minimal statistical-mechanical framework for field-controlled self-assembly of tunable patterns by magnetically heterogeneous polymers. They may also serve as a simple platform to investigate the coupling between internal epigenetic-like states and chromatin folding.
format Preprint
id arxiv_https___arxiv_org_abs_2602_22382
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Field-induced phase transitions in ferro-antiferromagnetic diblock copolymers
Raiola, Alberto
Locatelli, Emanuele
Marenduzzo, Davide
Orlandini, Enzo
Soft Condensed Matter
We study the equilibrium properties of a model of magnetic diblock copolymer where each monomer is decorated with an Ising-like spin. Spins interact ferromagnetically within each block and antiferromagnetically across blocks, generating frustration between magnetic ordering and spatial organization. By employing a mean-field approach and Monte Carlo simulations for self-avoiding walks on the cubic lattice, we investigate the system's response to an external magnetic field. We discover a rich phase diagram that includes: a swollen phase with both filaments magnetically disordered and spatially extended; a mixed compact phase characterized by a single globule in which the two filaments are strongly intertwined; a segregated compact phase composed of two globular, magnetically ordered, and spatially separated blocks. Further, if the magnitude of the intra-block ferromagnetic interaction differs between the two blocks, we observe a hybrid segregated (``tadpole'') phase where one extended block coexists with a collapsed one. Mean-field predictions are in quantitative agreement with Monte Carlo results for the location of the phase boundaries. These findings provide a minimal statistical-mechanical framework for field-controlled self-assembly of tunable patterns by magnetically heterogeneous polymers. They may also serve as a simple platform to investigate the coupling between internal epigenetic-like states and chromatin folding.
title Field-induced phase transitions in ferro-antiferromagnetic diblock copolymers
topic Soft Condensed Matter
url https://arxiv.org/abs/2602.22382