Thermodynamic phase transitions in a frustrated magnetic metamaterial.
Thermodynamic phase transitions in a frustrated magnetic metamaterial.
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DOI：
10.1038/ncomms9278
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发表时间：
2015-09-21
影响因子：
16.6
通讯作者：
Heyderman LJ
中科院分区：
文献类型：
--
作者：
Anghinolfi L;Luetkens H;Perron J;Flokstra MG;Sendetskyi O;Suter A;Prokscha T;Derlet PM;Lee SL;Heyderman LJ
具有相互作用的磁自由度的材料显示出丰富多样的磁行为，可以导致新颖的集体平衡和失衡现象。在平衡状态下，热力学相出现相关的相变，提供了潜在的集体行为的特征签名。在这里，我们创建了一个热活性人工可果美自旋冰，它是由一个大阵列的偶极相互作用的纳米磁体，并经历相变预测的微观理论。我们使用低能量μ介子光谱探测相互作用的纳米磁体的动态行为，并观察μ介子弛豫速率的峰值，可以确定与预测的相变的临界温度。这提供了实验证据，证明受抑磁性超材料可以被设计成允许热力学相。最近，已经建立了具有非线性磁化的热活性纳米磁体的周期性阵列，其模仿受抑磁体的行为并模拟伊辛系统。在这里，作者使用μ子自旋弛豫来证明人工戈薇冰系统中的热力学相变。
Materials with interacting magnetic degrees of freedom display a rich variety of magnetic behaviour that can lead to novel collective equilibrium and out-of-equilibrium phenomena. In equilibrium, thermodynamic phases appear with the associated phase transitions providing a characteristic signature of the underlying collective behaviour. Here we create a thermally active artificial kagome spin ice that is made up of a large array of dipolar interacting nanomagnets and undergoes phase transitions predicted by microscopic theory. We use low energy muon spectroscopy to probe the dynamic behaviour of the interacting nanomagnets and observe peaks in the muon relaxation rate that can be identified with the critical temperatures of the predicted phase transitions. This provides experimental evidence that a frustrated magnetic metamaterial can be engineered to admit thermodynamic phases. Recently, periodic arrays of thermally active nanomagnets with bistable magnetization have been built which mimic the behaviour of frustrated magnets and model Ising systems. Here, the authors use muon spin relaxation to evidence thermodynamic phase transitions in an artificial kagome ice system.