Designing Quantum Spin-Orbital Liquids in Artificial Mott Insulators.
Designing Quantum Spin-Orbital Liquids in Artificial Mott Insulators.
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DOI：
10.1038/srep31737
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发表时间：
2016-08-24
影响因子：
4.6
通讯作者：
Uchoa B
中科院分区：
文献类型：
--
作者：
Dou X;Kotov VN;Uchoa B
量子自旋轨道液体是难以捉摸的强相关状态的物质，出现自旋和轨道自由度之间的量子挫折。观察这些状态的一个有希望的途径是创造人工莫特绝缘体，在那里可以设计自旋和轨道之间的反铁磁相关性。我们证明了在蜂窝衬底上的库仑杂质晶格，例如在SiC上的石墨烯，可以用来模拟SU(4)对称自旋轨道晶格模型。我们利用了大质量狄拉克费米子在库仑杂质附近形成具有自旋和谷简并的中隙束缚态的性质。由于电子斥力的存在，杂质晶格的反铁磁相关是由具有SU(4)对称性的超交换相互作用驱动的，这种超交换相互作用产生于四分之一填充时的束缚态简并。我们提出量子自旋轨道液体可以在人工设计的固态系统中进行工程设计，其温度远远高于在冷原子光学晶格中实现的温度。我们讨论了不同几何形状的库仑杂质晶格中候选量子自旋液体的实验装置和可能的情况。
Quantum spin-orbital liquids are elusive strongly correlated states of matter that emerge from quantum frustration between spin and orbital degrees of freedom. A promising route towards the observation of those states is the creation of artificial Mott insulators where antiferromagnetic correlations between spins and orbitals can be designed. We show that Coulomb impurity lattices on the surface of gapped honeycomb substrates, such as graphene on SiC, can be used to simulate SU(4) symmetric spin-orbital lattice models. We exploit the property that massive Dirac fermions form mid-gap bound states with spin and valley degeneracies in the vicinity of a Coulomb impurity. Due to electronic repulsion, the antiferromagnetic correlations of the impurity lattice are driven by a super-exchange interaction with SU(4) symmetry, which emerges from the bound states degeneracy at quarter filling. We propose that quantum spin-orbital liquids can be engineered in artificially designed solid-state systems at vastly higher temperatures than achievable in optical lattices with cold atoms. We discuss the experimental setup and possible scenarios for candidate quantum spin-liquids in Coulomb impurity lattices of various geometries.