高温超导体掺杂过程中磁涨落和超导涨落的演化

Evolution of magnetic and superconducting fluctuations with doping of high-Tc superconductors.

作者信息

Blumberg G, Kang M, Klein MV, Kadowaki K, Kendziora C

机构信息

G. Blumberg, NSF Science and Technology Center for Superconductivity and Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA, and Institute of Chemical Physics and Biophysics, Tallinn EE0001, Estoni.

出版信息

Science. 1997 Nov 21;278(5342):1427-32. doi: 10.1126/science.278.5342.1427.

DOI:10.1126/science.278.5342.1427

PMID:9367948

Abstract

Electronic Raman scattering from high- and low-energy excitations was studied as a function of temperature, extent of hole doping, and energy of the incident photons in Bi2Sr2CaCu2O8+/-delta superconductors. For underdoped superconductors, short-range antiferromagnetic (AF) correlations were found to persist with hole doping, and doped single holes were found to be incoherent in the AF environment. Above the superconducting (SC) transition temperature Tc, the system exhibited a sharp Raman resonance of B1g symmetry and energy of 75 millielectron-volts and a pseudogap for electron-hole excitations below 75 millielectron-volts, a manifestation of a partially coherent state forming from doped incoherent quasi particles. The occupancy of the coherent state increases with cooling until phase ordering at Tc produces a global SC state.

摘要

在Bi2Sr2CaCu2O8±δ超导体中，研究了来自高能和低能激发的电子拉曼散射与温度、空穴掺杂程度以及入射光子能量的函数关系。对于欠掺杂超导体，发现短程反铁磁（AF）关联随着空穴掺杂而持续存在，并且发现掺杂的单空穴在AF环境中是不相干的。在超导（SC）转变温度Tc以上，系统表现出B1g对称性、能量为75毫电子伏特的尖锐拉曼共振以及低于75毫电子伏特的电子-空穴激发的赝能隙，这是由掺杂的非相干准粒子形成的部分相干态的一种表现。相干态的占有率随着冷却而增加，直到在Tc处的相位有序化产生全局SC态。