Antiferromagnetic chiral spin density wave and strain-induced Chern insulator in the square lattice Hubbard model with frustration
Antiferromagnetic chiral spin density wave and strain-induced Chern insulator in the square lattice Hubbard model with frustration
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DOI：
10.1103/physrevb.102.195120
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发表时间：
2019-11
影响因子：
3.7
通讯作者：
Yun-Peng Huang;Jinming Dong;P. Kotetes;Sen Zhou
中科院分区：
文献类型：
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作者：
Yun-Peng Huang;Jinming Dong;P. Kotetes;Sen Zhou
我们采用Hartree-Fock近似确定了阻挫正方晶格上Hubbard模型的磁基态。我们研究了相图作为库仑排斥强度U$的函数，以及最近和次最近邻跳跃之间的比率t$和t '$。在半填充和足够大的$U$，一个反铁磁手征自旋密度波序与非零自旋手征出现在一个广泛的制度的相图接近$t '/t=1/\sqrt{2}$，费米面是嵌套良好的波矢量$（\pi，\pi）$和$（\pi，0）/（0，\pi）$的基态。在较小和较大的$t '/t$下，该三重${\bfQ}$手性相分别被单Neel相和双共面自旋涡旋晶体相夹在中间.手征自旋密度波相位的能谱由四对简并带组成。这就产生了两对在布里渊区的点$（{\pi \over 2}，{\pi\over 2}）$具有相同手征的狄拉克锥。我们证明，对角应变的应用程序诱导$d_{xy}$-波次近邻跳跃，反过来，打开两个狄拉克锥与相反的质量差距。结果，出现了四对分离良好的拓扑非平凡带，每对都贡献了一个陈氏数$\pm1$。在半填充，这导致一个零总陈数，并呈现拓扑novirregional属性观察到的交流响应制度。相反，我们表明，在3/4$填充，三重-${\bf Q}$手征相产生陈绝缘体表现出量子反常霍尔效应。
We employ the Hartree-Fock approximation to identify the magnetic ground state of the Hubbard model on a frustrated square lattice. We investigate the phase diagram as a function of the Coulomb repulsion's strength $U$, and the ratio $t'/t$ between the nearest and next nearest neighbor hoppings $t$ and $t'$. At half-filling and for a sufficiently large $U$, an antiferromagnetic chiral spin density wave order with nonzero spin chirality emerges as the ground state in a wide regime of the phase diagram near $t'/t=1/\sqrt{2}$, where the Fermi surface is well-nested for both $(\pi,\pi)$ and $(\pi,0)/(0,\pi)$ wave vectors. This triple-${\bf Q}$ chiral phase is sandwiched by a single-${\bf Q}$ Neel phase and a double-${\bf Q}$ coplanar spin-vortex crystal phase, at smaller and larger $t'/t$, respectively. The energy spectrum in the chiral spin density wave phase consists of four pairs of degenerate bands. These give rise to two pairs of Dirac cones with the same chirality at the point $({\pi \over 2},{\pi\over 2})$ of the Brillouin zone. We demonstrate that the application of a diagonal strain induces a $d_{xy}$-wave next nearest neighbor hopping which, in turn, opens gaps in the two Dirac cones with opposite masses. As a result, four pairs of well-separated topologically-nontrivial bands emerge, and each pair of those contributes with a Chern number $\pm1$. At half-filling, this leads to a zero total Chern number and renders the topologically-notrivial properties observable only in the ac response regime. Instead, we show that at $3/4$ filling, the triple-${\bf Q}$ chiral phase yields a Chern insulator exhibiting the quantum anomalous Hall effect.