低摻雜銅氧超導體的中間能階態

Abstract

近期一個由P. Cai以及共同研究者，在低摻雜Bi-2201材料上的掃描穿隧能譜實驗，在氧的p軌域能帶和銅的upper Hubbard band(UHB)的能級中間發現了一些高能量的中間能階態的訊號。實驗結果顯示了這些中間能階態以及UHB之間在能量與光譜權重上的相互關係。在本論文中我們提出了一個簡潔的理論來解釋這些中間能階態的來源，並且藉由建立它們與UHB的形式來計算應證。我們的計算結果在隨摻雜濃度的演化上與實驗吻合。

A recent Scanning Tunneling Spectra (STS) measurement on underdoped Bi-2201 by Cai et al., discovered large energy in-gap states between Oxygen band and upper Hubbard band (UHB) of Cu. There is a strong interplay between the spectral weights and energies of the UHB and these in-gap states. We proposed a simple theory to explain the origin of these states by constructing explicitly the in-gap states and UHB states for a one-band Hubbard model. Our results show that the spatial variation of in-gap states and its evolution of spectral weight transfer from UHB are associated with the inhomogeneous local hole density.