标题： 受限几何中奈尔斯kyrmions的简并性和涨落 显示英文标题

标题： Degeneracies and fluctuations of Néèl skyrmions in confined geometries

摘要： 最近在具有垂直磁各向异性的层状磁性材料中发现可调的Dzyaloshinskii-Moriya相互作用，使它们成为在高温下稳定和操控自旋子的有前途的候选材料。 在本文中，我们使用蒙特卡罗模拟研究这些材料中自旋子对热涨落和有限尺寸效应的鲁棒性。 我们发现，在受限几何结构和有限温度下，自旋子在相图的大部分区域存在。 此外，我们发现与无限大的系统相比，受限几何结构更有利于自旋子而非螺旋相。 通过调节磁场穿过自旋子相，系统会经历一系列磁结构的转变，经过不同数量的自旋子、伸长的自旋子和半自旋子以及螺旋状态。 我们考虑量子和热涨落如何消除这些转变中出现的简并性，并发现通常由涨落更倾向于具有更多自旋子的状态而不是具有较少自旋子的状态。 最后，我们评论了通过拓扑和异常霍尔效应检测各种相的电学方法。 显示英文摘要

摘要： The recent discovery of tunable Dzyaloshinskii-Moriya interactions in layered magnetic materials with perpendicular magnetic anisotropy makes them promising candidates for stabilization and manipulation of skyrmions at elevated temperatures. In this article, we use Monte Carlo simulations to investigate the robustness of skyrmions in these materials against thermal fluctuations and finite-size effects. We find that in confined geometries and at finite temperatures skyrmions are present in a large part of the phase diagram. Moreover, we find that the confined geometry favors the skyrmion over the spiral phase when compared to infinitely large systems. Upon tuning the magnetic field through the skyrmion phase, the system undergoes a cascade of transitions in the magnetic structure through states of different number of skyrmions, elongated and half-skyrmions, and spiral states. We consider how quantum and thermal fluctuations lift the degeneracies that occur at these transitions, and find that states with more skyrmions are typically favored by fluctuations over states with less skyrmions. Finally, we comment on electrical detection of the various phases through the topological and anomalous Hall effects.