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arXiv 2602.22382cond-mat.soft
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磁场诱导的铁磁-反铁磁双块聚合物相变

Field-induced phase transitions in ferro-antiferromagnetic diblock copolymers

Dipartimento di Fisica e Astronomia and Sezione INFN, Università di Padova(帕多瓦大学物理与天文学系及INFN分部);SUPA, School of Physics and Astronomy, University of Edinburgh(爱丁堡大学物理与天文学院)

Alberto Raiola, Emanuele Locatelli, Davide Marenduzzo, Enzo Orlandini

AI总结:

该研究通过磁场调控铁磁-反铁磁双块聚合物的相变,揭示了不同磁相互作用下聚合物自组装的复杂相图。

摘要:

我们研究了一种磁性双块聚合物模型的平衡性质,其中每个单体都装饰有类似伊辛的自旋。自旋在每个块内发生铁磁相互作用,在块间发生反铁磁相互作用,产生磁序与空间组织之间的摩擦。通过采用平均场方法和在立方晶格上进行的自回避行走蒙特卡洛模拟,我们研究了系统对外部磁场的响应。我们发现了一个丰富的相图,包括:一个肿胀相,其中纤维磁性无序且空间扩展;一个混合紧密相,其特征是单个球形结构,其中两个纤维强烈交织;一个分离紧密相,由两个球形、磁性有序且空间分离的块组成。进一步,如果两个块内的铁磁相互作用强度不同,我们观察到一个混合分离(“奶牛”)相,其中一个扩展块与一个坍缩块共存。平均场预测与蒙特卡洛结果在相界位置上定量一致。这些发现提供了一个最小的统计力学框架,用于通过磁性异质聚合物控制自组装可调图案。它们也可能成为研究内部表观遗传状态与染色质折叠耦合的简单平台。

英文摘要:

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.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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