Abstract:

The mechanism of high temperature cuprates superconductivity remains an outstanding puzzle despite 30 years of research. A key task in unveiling this mystery is to understand the electronic structure evolution from the doped Mott insulator perspective. In this talk, we report scanning tunneling microscopy studies of the atomic electronic structure of cuprates with increasing doping levels. We first discuss the charge transfer gap in the parent Mott insulator, and its anticorrelation with the maximum transition temperature, implying the central role of superexchange interaction in mediating the Cooper pairing. We then show how the low energy electronic states emerge within the charge transfer gap when few holes are introduced, which can be regarded as hydrogen atom and molecule in a Mott insulator background. The doped few percent of holes self-assemble into small islands of checkerboard. Even in the insulating sample, we observe a small superconducting-like gap when approaching the checkerboard island. Across the insulator to superconductor transition, we observe the enhancement of quasiparticle interferences characteristic of long-range phase coherence. We find that each checkerboard puddle contains approximately two holes, and exhibits stripy internal patterns that have strong influence on the superconducting properties. With further increase of doping into the overdoped regime, the strong quasiparticle scattering in the antinodal region causes pair breaking, which is the driving force for the vanishing of superconductivity.

Bio:

王亞愚，1998年本科畢業(yè)于中國科技大學(xué)物理系，2004年在美國普林斯頓大學(xué)物理系獲得博士學(xué)位，2004年至2007年在美國加州大學(xué)伯克利分校物理系任Miller Research Fellow，2007年加入清華大學(xué)物理系任教授至今。研究領(lǐng)域為凝聚態(tài)物理實驗，近期的主要研究方向為拓?fù)淞孔硬牧系妮斶\(yùn)性質(zhì)和高溫超導(dǎo)體的掃描隧道顯微學(xué)研究。曾獲得William McMillan Award、“馬丁-伍德爵士中國獎”、中國物理學(xué)會“黃昆物理獎”、國家自然科學(xué)一等獎（第二完成人）、騰訊“科學(xué)探索獎”、入選新基石研究員。