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Optical Study of Crystal‐Field Excitation in (R)Ba 2 Cu 3 O 7–δ Single Crystals
Author(s) -
Martin A.A.,
Cardona M.,
Jandl S.,
Nekvasil V.,
Wolf Th.
Publication year - 2000
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200007)220:1<475::aid-pssb475>3.0.co;2-d
Subject(s) - superconductivity , phonon , raman spectroscopy , excitation , crystal (programming language) , coupling (piping) , ion , condensed matter physics , field (mathematics) , spectroscopy , materials science , range (aeronautics) , atomic physics , physics , optics , mathematics , quantum mechanics , computer science , pure mathematics , metallurgy , composite material , programming language
A large number of high‐temperature superconductors (HTS) contain rare‐earth (R) ions with 4f‐electron multiplets which are split by the crystal field (CF) of the neighboring ligands and, in many cases, their energy differences are in the range of optical phonons. When these two excitations (phonons and CF) have the same symmetry and are close in energy they can couple to each other, leading to a doublet structure at low temperature. Since the R ions are located between the CuO 2 superconducting planes, this crystal‐field–phonon coupling can be used as a probe to investigate superconductivity related phenomena. In this paper, we discuss the coupling of phonons to CF excitations in (R)Ba 2 Cu 3 O 7– δ and demonstrate that Raman and infrared spectroscopy can be successfully used as a novel tool for CF studies in HTS, since they are not limited to low energy transfer and can be applied to study small single crystals.