Combescot Monique, Combescot Roland, Alloing Mathieu, Dubin François
Institut des NanoSciences de Paris, Université Pierre et Marie Curie, CNRS, Tour 22, 4 Place Jussieu, 75005 Paris, France.
Laboratoire de Physique Statistique, Ecole Normale Supérieure, UPMC Paris 06, Université Paris Diderot, CNRS, 24 Rue Lhomond, 75005 Paris, France.
Phys Rev Lett. 2015 Mar 6;114(9):090401. doi: 10.1103/PhysRevLett.114.090401. Epub 2015 Mar 4.
Exchange interaction is responsible for the stability of elementary boson condensates with respect to momentum fragmentation. This remains true for composite bosons when single fermion exchanges are included but spin degrees of freedom are ignored. Here, we show that their inclusion can produce a spin fragmentation of the dark exciton condensate, i.e., an unpolarized condensate with an equal amount of spin (+2) and (-2) excitons not coupled to light. The composite boson many-body formalism allows us to predict that, for spatially indirect excitons, the condensate polarization switches from unpolarized to fully polarized when the distance between the layers confining electrons and holes increases. Importantly, the threshold distance for this switch lies in a regime fully accessible to experiments.
交换相互作用负责基本玻色子凝聚体相对于动量碎片化的稳定性。当包含单费米子交换但忽略自旋自由度时，对于复合玻色子也是如此。在这里，我们表明包含自旋自由度会导致暗激子凝聚体的自旋碎片化，即一种未极化的凝聚体，其中具有等量的不与光耦合的自旋为（+2）和（-2）的激子。复合玻色子多体形式理论使我们能够预测，对于空间间接激子，当限制电子和空穴的层之间的距离增加时，凝聚体极化从不极化转变为完全极化。重要的是，这种转变的阈值距离处于实验完全可及的范围内。
