论文标题
石墨中激子的玻色子凝结的临界点
Critical point for Bose-Einstein condensation of excitons in graphite
论文作者
论文摘要
激子是通过有吸引力的库仑相互作用结合的电子孔对。在许多情况下，各种实验探针都检测到了短暂的激子。一种激子绝缘子是这种激子的集体状态，更加难以捉摸。在这里，由于脉冲磁场中的Nernst测量值，我们表明在石墨中有临界温度（t = 9.2 K），而抗激元的Bose-Einstein凝结有一个临界温度（t = 9.2 K）（B = 47 T）。在这个关键场上，孔和电子兰道子带同时越过费米水平并允许激子形成。通过量化基底平面中激子的有效质量和空间分离，我们表明激发液的退化温度与此临界温度相对应。该识别将解释为什么在石墨中观察到的场诱导的过渡不是超出量子极限的三维电子系统的通用特征。
An exciton is an electron-hole pair bound by attractive Coulomb interaction. Short-lived excitons have been detected by a variety of experimental probes in numerous contexts. An excitonic insulator, a collective state of such excitons, has been more elusive. Here, thanks to Nernst measurements in pulsed magnetic fields, we show that in graphite there is a critical temperature (T = 9.2 K) and a critical magnetic field (B = 47 T) for Bose-Einstein condensation of excitons. At this critical field, hole and electron Landau sub-bands simultaneously cross the Fermi level and allow exciton formation. By quantifying the effective mass and the spatial separation of the excitons in the basal plane, we show that the degeneracy temperature of the excitonic fluid corresponds to this critical temperature. This identification would explain why the field-induced transition observed in graphite is not a universal feature of three-dimensional electron systems pushed beyond the quantum limit.
