Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: Superconductivity: Properties and Electronic Structure
TT 6.9: Vortrag
Montag, 7. März 2016, 12:15–12:30, H19
The collapse of the columnar spatial topology of pseudogap excitations in the underdoped-overdoped transition of cuprate superconductors — •Jürgen Röhler — Universität zu Köln, 50937 Köln, Germany
The intensity IQ0 of the Q=0 nematic pseudogap excitations in Bi2Sr2CaCu2O8+x was found to increase between p≥ 0.06 and 0.14 and to collapse at popt=0.16, reaching zero at p=0.2 [1]. Evidentally it maps the growth and the collapse of the bulge in the doping dependence of the basal-plane area (ab) of p-type cuprates [2]. The nematic topology of the pseudogap
excitations results from the non-occupancy constraint for nn ZR-holes
excluding 1a dimerization, but favoring 3a pair states with inequivalent Ox,y sites. 3a pair states have hard core properties [3], yield d-type CDW excitations, and inflate the basal-plane area by a columnar topology against covalency-driven contraction. We show that optimal delocalization of ZR-holes at popt=1/6≃ 0.17, tantamount to maximal connectedness of 3a pair states, will transform the columnar nematic pattern into isotropic tweedy striations, hence collapses IQ0, and the bulge.
K. Fujita et al., Science 344, 612 (2015).
J. Röhler, J. Superconductivity 17, 159 (2004).
J. Röhler, Int. Mod. Phys. B19, 255 (2005).