Distinct Behaviors of Inner and Outer CuO2 Planes in Quadruple-Layer Cuprate (Cu,C)Ba2Ca3Cu4O11+δ

Abstract

The superconducting transition temperatures (Tc’s) of trilayer or quadruple-layer cuprates typically surpass those of single-layer or bilayer systems. However, the lack of direct electronic-structure and superconducting-gap measurements in optimal-Tc quadruple-layer cuprates has impeded a comprehensive understanding of the origin of the enhanced Tc in multilayer systems. In this Letter, using angle-resolved photoemission spectroscopy, we investigate the quadruple-layer cuprate (Cu,C)Ba2Ca3Cu4O11+δ (CuC-1234) with a high Tc of 110 K, and resolved distinct superconducting-gap behaviors between the inner CuO2 planes and outer CuO2 planes, in contrast to that reported for trilayer cuprates. Outer CuO2 planes develop their own superconducting gap and superconducting coherence peak at a temperature much lower than the Tc of the material, while the large pairing strength and phase coherence concurrently emerge at the underdoped inner CuO2 planes at Tc. Our findings suggest that CuO2 planes free of apical oxygen can have significant contribution to superconductivity up to 110 K in multilayer cuprates, even at a doping level of 0.07 holes per Cu, a level that lies deep in the underdoped regime of single- and bilayer cuprates. These findings provide new insights into the origin of high Tc in multilayer cuprates.

Source-reported materials — not catalogue approval

Similar papers