London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, 17-19 Gordon Street, London, WC1H 0AJ, UK.
Department of Innovation and Enterprise, University College London, 90 Tottenham Court Road, London, W1T 4TJ, UK.
Nat Commun. 2019 Mar 14;10(1):1219. doi: 10.1038/s41467-019-09187-w.
Vertex models are an important class of statistical mechanical system that admit exact solutions and exotic physics. Applications include water ice, ferro- and antiferro-electrics, spin ice and artificial spin ice. Here we show that it is possible to engineer spin ice films with atomic-layer precision down to the monolayer limit. Specific heat measurements show that these films, which have a fundamentally different symmetry to bulk spin ice, realise systems close to the two-dimensional F-model, with exotic phase transitions on topologically-constrained configurational manifolds. Our results show how spin ice thin films can release the celebrated Pauling entropy of spin ice without an anomaly in the specific heat. They also significantly expand the class of vertex models available to experiment.
顶点模型是一类重要的统计力学系统，具有精确解和奇异物理性质。应用包括水冰、铁电体和反铁电体、自旋冰和人工自旋冰。在这里，我们展示了通过原子层精度的工程手段来制备自旋冰薄膜，直至单层极限。比热测量表明，这些薄膜具有与体自旋冰根本不同的对称性，实现了接近二维 F 模型的系统，在拓扑约束的构型流形上具有奇异相变。我们的结果表明，自旋冰薄膜如何在比热中没有异常的情况下释放出著名的泡利自旋冰熵。它们还显著扩展了可供实验使用的顶点模型的类别。
