Emergent magnetic monopoles in frustrated magnetic systems.
Emergent magnetic monopoles in frustrated magnetic systems.
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受挫磁系统中出现的磁单极子。
DOI：
10.1098/rsta.2011.0403
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Branford WR
中科院分区：
文献类型：
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作者：
Branford WR
本主题刊报道了在一个讨论会上发表的论文，该会议旨在将研究磁荷载流子或单极子的理论家和实验家聚集在一起，研究自然和人工纳米结构自旋冰格中的磁荷载流子或单极子，并探讨有关贝里相物理和畴壁运动的相关主题，以及这些系统中可能的固态/宇宙学界面。讨论会议在皇家学会Kavli中心举行，组织者感谢所有参与这个奇妙的新科学论坛发展的人。Rajantie[1]回顾了宇宙学中的磁单极子，并讨论了宇宙学与自旋冰中固体状态之间存在界面的可能性。他描述了在标准模型之外的许多粒子物理理论中对磁单极子存在的预测，以及它们缺乏实验或观测迹象的情况。他回顾了磁单极子在量子场论中的作用，并讨论了它们对粒子物理学和宇宙学的影响。他还强调了它们与在受挫磁系统中发现的单极子的异同。最近在自旋冰中发现的有效磁单极子准粒子提出了一个问题，即人们是否可以利用它们进一步推动这些理论进展。虽然准粒子在许多方面确实表现得像基本的磁单极子粒子，但很明显它们之间有重要的区别。也许最重要的是，连接单极子的狄拉克弦并非完全非物理的。这并不意味着人们不能用自旋冰实验来得出关于基本单极子的结论，但人们必须意识到系统之间的差异以及它们所施加的限制。因此，随机热波动发挥重要作用的情况似乎最有希望，例如研究相变中单极子的形成。Chern & Tchernyshyov等人在角共享三角形的二维晶格kagome上对自旋冰的磁有序进行了数值研究。磁铁是一个六态时钟模型，有六个基态，排序发生在两个阶段。在与第二邻体有短程相互作用的自旋冰中，Kosterlitz-Thouless跃迁将中间临界相与顺磁相和有序相分离。在偶极自旋冰中，中间相具有长时间的交错磁荷序。
This Theme Issue reports papers presented at a Discussion Meeting intended to bring together theorists and experimentalists working on magnetic charge carriers, or monopoles, in both natural and artificially nanostructured spin ice lattices, and to explore related topics on Berry phase physics and domain wall motion and a possible solid-state/cosmology interface in these systems. The Discussion Meeting was held in the Royal Society Kavli Centre and the organizers thank all those involved in the development of this marvellous new scientific forum.Rajantie [1] reviews magnetic monopoles in cosmology and discusses the possibility of an interface between cosmology and a solid state in spin ices. He describes the predictions of the existence of magnetic monopoles in many theories of particle physics beyond the Standard Model, and the absence of experimental or observational sign of them. He reviews the role of magnetic monopoles in quantum field theory and discusses their implications for particle physics and cosmology. He also highlights their differences from and similarities to monopoles found in frustrated magnetic systems. The recent discovery of effective magnetic monopole quasiparticles in spin ices raises the question of whether one could make use of them to take these theoretical advances further. Although the quasiparticles do behave in many ways like fundamental magnetic monopole particles, it is also clear that there are important differences. Perhaps most importantly, the Dirac strings connecting the monopoles are not completely unphysical. This does not mean that one cannot use spin ice experiments to draw conclusions for fundamental monopoles, but one has to be aware of the differences between the systems and the limitations they impose. Situations in which random thermal fluctuations play an important role would therefore appear most promising, such as studying the formation of monopoles in phase transitions. Chern & Tchernyshyov [2] present a numerical study of magnetic ordering in spin ice on kagome, a two-dimensional lattice of corner-sharing triangles. The magnet is a six-state clock model and has six ground states, with the ordering occurring in two stages. In spin ice with short-range interactions up to second neighbours, Kosterlitz–Thouless transitions separate an intermediate critical phase from the paramagnetic and ordered phases. In dipolar spin ice, the intermediate phase has a long-range order of staggered magnetic charges.