Physical realization of a quantum spin liquid based on a complex frustration mechanism
Physical realization of a quantum spin liquid based on a complex frustration mechanism
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DOI：
10.1038/nphys3826
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发表时间：
2016-10-01
期刊：
影响因子：
19.6
通讯作者：
Ryll, Hanjo
中科院分区：
文献类型：
--
作者：
Balz, Christian;Lake, Bella;Ryll, Hanjo
与传统的磁铁不同，磁矩在基态是部分或完全静止的，在量子自旋液体中，它们在最低温度下保持集体运动。这种状态的重要性在于它是相干的，并且高度纠缠，而不会破坏局部对称性。在具有各向同性相互作用的磁体的情况下，在具有反铁磁相互作用的简单晶格中寻求自旋液体行为，所述反铁磁相互作用有利于磁矩的反平行排列并且与晶格几何形状不相容。尽管进行了广泛的研究，但实验性的实现仍然很少。在这里，我们调查的新的，未开发的磁铁Ca10Cr7O28，它有一个复杂的哈密顿量组成的几个不同的各向同性的相互作用和铁磁耦合比反铁磁的强。我们从实验和理论上证明了它具有量子自旋液体的所有特性。因此，各向同性磁体中的自旋液体行为并不局限于目前研究的简单理想化模型，而是可以与复杂结构和铁磁相互作用兼容。
Unlike conventional magnets where the magnetic moments are partially or completely static in the ground state, in a quantum spin liquid they remain in collective motion down to the lowest temperatures. The importance of this state is that it is coherent and highly entangled without breaking local symmetries. In the case of magnets with isotropic interactions, spin liquid behaviour is sought in simple lattices with antiferromagnetic interactions that favour antiparallel alignments of the magnetic moments and are incompatible with the lattice geometries. Despite an extensive search, experimental realizations remain very few. Here we investigate the novel, unexplored magnet Ca10Cr7O28, which has a complex Hamiltonian consisting of several different isotropic interactions and where the ferromagnetic couplings are stronger than the antiferromagnetic ones. We show both experimentally and theoretically that it displays all the features expected of a quantum spin liquid. Thus spin-liquid behaviour in isotropic magnets is not restricted to the simple idealized models currently investigated, but can be compatible with complex structures and ferromagnetic interactions.