Garanin Dmitry A, Soriano Jorge F, Chudnovsky Eugene M
Physics Department, Herbert H. Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468-1589, United States of America.
J Phys Condens Matter. 2024 Aug 30;36(47). doi: 10.1088/1361-648X/ad6f8b.
We report comprehensive Monte-Carlo studies of the melting of skyrmion lattices (SkL) in systems of small, medium, and large sizes with the number of skyrmions ranging from 10to over 10. Large systems exhibit hysteresis similar to that observed in real experiments on the melting of SkLs. For sufficiently small systems which achieve thermal equilibrium, a fully reversible sharp solid-liquid transition on temperature with no intermediate hexatic phase is observed. A similar behavior is found on changing the magnetic field that provides the control of pressure in the SkL. We find that on heating the melting transition occurs via a formation of grains with different orientations of hexagonal axes. On cooling, the fluctuating grains coalesce into larger clusters until a uniform orientation of hexagonal axes is slowly established. The observed scenario is caused by collective effects involving defects and is more complex than a simple picture of a transition driven by the unbinding and annihilation of dislocation and disclination pairs.
我们报告了对不同尺寸（小、中、大）且具有10到超过10个以上斯格明子的系统中斯格明子晶格（SkL）熔化的全面蒙特卡罗研究。大型系统表现出与在斯格明子晶格熔化的实际实验中观察到的类似滞后现象。对于足够小且达到热平衡的系统，观察到在温度上有完全可逆的尖锐固 - 液转变，且没有中间的六方相。在改变提供对斯格明子晶格压力控制的磁场时也发现了类似行为。我们发现，加热时熔化转变通过形成具有不同六方轴取向的晶粒而发生。冷却时，波动的晶粒聚合成更大的团簇，直到六方轴的均匀取向缓慢建立。观察到的这种情况是由涉及缺陷的集体效应引起的，并且比由位错和 disclination 对的解束缚和湮灭驱动的简单转变图像更为复杂。
