Laurell Pontus, Fiete Gregory A
Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA.
Phys Rev Lett. 2017 Apr 28;118(17):177201. doi: 10.1103/PhysRevLett.118.177201. Epub 2017 Apr 26.
We theoretically study the magnetic properties of pyrochlore iridate bilayer and trilayer thin films grown along the [111] direction using a strong coupling approach. We find the ground state magnetic configurations on a mean field level and carry out a spin-wave analysis about them. In the trilayer case the ground state is found to be the all-in-all-out (AIAO) state, whereas the bilayer has a deformed AIAO state. For all parameters of the spin-orbit coupled Hamiltonian we study, the lowest magnon band in the trilayer case has a nonzero Chern number. In the bilayer case we also find a parameter range with nonzero Chern numbers. We calculate the magnon Hall response for both geometries, finding a striking sign change as a function of temperature. Using a slave-boson mean-field theory we study the doping of the trilayer system and discover an unconventional time-reversal symmetry broken d+id superconducting state. Our study complements prior work in the weak coupling limit and suggests that the [111] grown thin film pyrochlore iridates are a promising candidate for topological properties and unconventional orders.
我们采用强耦合方法从理论上研究了沿[111]方向生长的焦绿石铱酸盐双层和三层薄膜的磁性。我们在平均场水平上找到了基态磁构型，并对其进行了自旋波分析。在三层的情况下，基态被发现是全进全出（AIAO）态，而双层则具有变形的AIAO态。对于我们研究的自旋轨道耦合哈密顿量的所有参数，三层情况下最低的磁振子带具有非零的陈数。在双层情况下，我们也发现了一个具有非零陈数的参数范围。我们计算了两种几何结构的磁振子霍尔响应，发现其作为温度的函数有显著的符号变化。使用从玻色子平均场理论，我们研究了三层系统的掺杂，并发现了一种非常规的时间反演对称性破缺的d+id超导态。我们的研究补充了弱耦合极限下的先前工作，并表明沿[111]生长的薄膜焦绿石铱酸盐是拓扑性质和非常规序的有前途的候选材料。
