Magnetic Raman scattering in cuprate antiferromagnetic insulators and doped superconductors

Girsh Blumberg, Peter Michael Abbamonte, Miles V. Klein

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

We present results of low-temperature two-magnon resonance Raman excitation profile measurements for single layer Sr 2CuO 2Cl 2 and bilayer YBa 2Cu 3O 6.1 antiferromagnets over the excitation region from 1.65 to 3.05 eV. These data reveal composite structure of the two-magnon line shape with peaks at approximately 2.8 and approximately 4 J and strong nonmonotic dependence of the scattering intensity on excitation energy. We analyze these data using the triple resonance theory of Chubukov and Frenkel [Phys. Rev. Lett., 74, 3057 (1995)] and deduce information about magnetic interaction and electronic band parameters in these antiferromagnetic insulators. We study the evolution of the magnetic excitation with hole doping in CuO 2 planes of YBa 2Cu 3O 6+δ and YBa 2Cu 40 8 single crystals. We find that the spin excitations at energy approximately equal to 3 J, similar to the two-magnon excitations in the insulators, persist with doping and are evidence that antiferromagnetic fluctuations with spatial extent of at least three lattice constants are not overdamped in the underdoped superconductors. The two-magnon resonance study shows the existence of the charge-transfer gap in the underdoped cuprates and provides information about evolution of electronic band parameters with doping. We report a magnetic Raman scattering study of YBa 2Cu 40 8 superconductor with substitution of Zn on the Cu(2) site. Two and five-tenths percent of substitution softens the two-magnon excitation frequency from 2900 to 2300 cm -1. This softening is attributed to the absence of a defined spin projection on at least one of eight Cu(2)/Zn sites involved in the superexchange, and it signifies that the Zn- introduced magnetic distortion extends to at lest four Cu sites neighboring a Zn site. The electronic Raman continuum intensity weakens with increasing Zn doping, manifesting a relationship between the Raman continuum and the spin fluctuations.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
EditorsI. Bozovic, D. van der Marel
Pages205-214
Number of pages10
Edition1/-
StatePublished - Dec 1 1996
EventSpectroscopic Studies of Superconductors. Part 2 (of 2) - San Jose, CA, USA
Duration: Jan 29 1996Feb 1 1996

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Number1/-
Volume2696

Other

OtherSpectroscopic Studies of Superconductors. Part 2 (of 2)
CitySan Jose, CA, USA
Period1/29/962/1/96

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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