Competing quantum paramagnetic ground states of the Heisenberg antiferromagnet on the star lattice
Competing quantum paramagnetic ground states of the Heisenberg antiferromagnet on the star lattice
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DOI：
10.1103/physrevb.81.134418
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发表时间：
2009-11
影响因子：
3.7
通讯作者：
Bohm-Jung Yang;A. Paramekanti;Yong Baek Kim
中科院分区：
文献类型：
--
作者：
Bohm-Jung Yang;A. Paramekanti;Yong Baek Kim
研究了二维星星晶格中海森堡反铁磁体的各种竞争顺磁基态。使用从粒子平均场理论结合投影对称群分析，我们研究了各种候选的自旋液体状态在这个晶格上，包括手征自旋液体，自旋液体与费米表面的自旋子，和双自旋液体，打破晶格旋转对称。受大N SU（N）理论以及数值精确对角化研究的启发，我们还研究了这种晶格上的各种价键固体（VBS）态。基于Gutzwiller投影态的能量学研究，我们发现完全带隙的自旋液体态是该模型的最低能量自旋液体候选者。我们还发现，从能量学的研究，使用Gutzwiller投影波函数和键算符的方法，这种自旋液体是不稳定的两个不同的VBS状态-一个VBS状态，尊重所有的哈密顿对称性和VBS状态，表现出$\sqrt {3}\times\sqrt {3}$顺序-取决于两个不等价的键的晶格上的海森堡交换耦合的比率。我们计算的三重子色散在两个VBS状态内的键操作员的方法，并讨论我们的工作可能产生的影响，为未来的实验候选材料。
We investigate various competing paramagnetic ground states of the Heisenberg antiferromagnet on the two dimensional star lattice which exhibits geometric frustration. Using slave particle mean field theory combined with a projective symmetry group analysis, we examine a variety of candidate spin liquid states on this lattice, including chiral spin liquids, spin liquids with Fermi surfaces of spinons, and nematic spin liquids which break lattice rotational symmetry. Motivated by connection to large-N SU(N) theory as well as numerical exact diagonalization studies, we also examine various valence bond solid (VBS) states on this lattice. Based on a study of energetics using Gutzwiller projected states, we find that a fully gapped spin liquid state is the lowest energy spin liquid candidate for this model. We also find, from a study of energetics using Gutzwiller projected wave functions and bond operator approaches, that this spin liquid is unstable towards two different VBS states -- a VBS state which respects all the Hamitonian symmetries and a VBS state which exhibits $\sqrt{3}\times\sqrt{3}$ order -- depending on the ratio of the Heisenberg exchange couplings on the two inequivalent bonds of the lattice. We compute the triplon dispersion in both VBS states within the bond operator approach and discuss possible implications of our work for future experiments on candidate materials.