Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
Institute for Theoretical Physics, Utrecht University, Princetonplein 5, 3584CC Utrecht, Netherlands.
Phys Rev Lett. 2019 Oct 18;123(16):167203. doi: 10.1103/PhysRevLett.123.167203.
Electrons and holes residing on the opposing sides of an insulating barrier and experiencing an attractive Coulomb interaction can spontaneously form a coherent state known as an indirect exciton condensate. We study a trilayer system where the barrier is an antiferromagnetic insulator. The electrons and holes here additionally interact via interfacial coupling to the antiferromagnetic magnons. We show that by employing magnetically uncompensated interfaces, we can design the magnon-mediated interaction to be attractive or repulsive by varying the thickness of the antiferromagnetic insulator by a single atomic layer. We derive an analytical expression for the critical temperature T_{c} of the indirect exciton condensation. Within our model, anisotropy is found to be crucial for achieving a finite T_{c}, which increases with the strength of the exchange interaction in the antiferromagnetic bulk. For realistic material parameters, we estimate T_{c} to be around 7 K, the same order of magnitude as the current experimentally achievable exciton condensation where the attraction is solely due to the Coulomb interaction. The magnon-mediated interaction is expected to cooperate with the Coulomb interaction for condensation of indirect excitons, thereby providing a means to significantly increase the exciton condensation temperature range.
位于绝缘势垒相对侧的电子和空穴，由于库仑相互吸引，会自发形成一种相干态，即间接激子凝聚体。我们研究了一种三层体系，其中势垒是一种反铁磁绝缘体。这里的电子和空穴还通过与反铁磁磁振子的界面耦合相互作用。我们表明，通过采用磁非补偿界面，通过改变反铁磁绝缘体的单层厚度，我们可以设计出具有吸引力或排斥力的磁振子介导相互作用。我们推导出了间接激子凝聚的临界温度 Tc 的解析表达式。在我们的模型中，各向异性对于实现有限的 Tc 至关重要，它随着反铁磁体中的交换相互作用强度的增加而增加。对于实际的材料参数，我们估计 Tc 约为 7 K，与目前实验上可实现的激子凝聚的相同量级，其中吸引力仅归因于库仑相互作用。磁振子介导的相互作用有望与库仑相互作用一起促进间接激子的凝聚，从而为显著提高激子凝聚温度范围提供了一种手段。
