开罗五角晶格上的量子磁性
Quantum magnetism on the Cairo pentagonal lattice
摘要：
我们提出了一个广泛的分析和数值研究的反铁磁海森堡模型上的开罗五边形晶格，对偶的Shastry-Sutherland晶格与密切实现的S=5/2化合物Bi 2Fe 4 O 9。考虑由晶格对称性所提出的具有两个交换耦合的模型，并研究了基态随交换耦合比x和自旋S变化的性质。在建立了经典相图之后，我们以一种渐进的方式打开了量子力学，这种方式突出了量子涨落在晶格的两个不等价位置上的不同作用。对于S=1/2，最重要的发现包括：（i）由于在小x处的潜在有序-无序机制（与J2 >> J1的涌现J1-J2有效模型有关），共线和四子晶格正交相位之间的令人惊讶的相互作用，以及（ii）在中间x处的非磁性和可能的自旋-非磁性相位，具有d波对称性。
英文摘要：
We present an extensive analytical and numerical study of the antiferromagnetic Heisenberg model on the Cairo pentagonal lattice, the dual of the Shastry-Sutherland lattice with a close realization in the S=5/2 compound Bi2Fe4O9. We consider a model with two exchange couplings suggested by the symmetry of the lattice, and investigate the nature of the ground state as a function of their ratio x and the spin S. After establishing the classical phase diagram we switch on quantum mechanics in a gradual way that highlights the different role of quantum fluctuations on the two inequivalent sites of the lattice. The most important findings for S=1/2 include: (i) a surprising interplay between a collinear and a four-sublattice orthogonal phase due to an underlying order-by-disorder mechanism at small x (related to an emergent J1-J2 effective model with J2 >> J1), and (ii) a non-magnetic and possibly spin-nematic phase with d-wave symmetry at intermediate x.
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