Raman scattering from spin fluctuations in Pr sub 2 minus x Ce sub x CuO sub 4 minus y , Nd sub 2 minus x Ce sub x CuO sub 4 minus y , and Sm sub 2 minus x Ce sub x CuO sub 4 minus y

Journal Article · Thu Jan 31 23:00:00 EST 1991 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.43.3009· OSTI ID:5637402

Tomeno, I; Yoshida, M; Ikeda, K; Tai, K; Takamuku, K; Koshizuka, N; Tanaka, S ^[1]; Oka, K; Unoki, H ^[2]

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1. Superconductivity Research Laboratory, International Superconductivity Technology Center, Shinonome, Koto-ku, Tokyo 135, Japan (JP)
2. Electrotechnical Laboratory, Umezono, Tsukuba, Ibaraki 305, (Japan)

Antiferromagnetic excitations in single crystals of Pr{sub 2{minus}{ital x}}Ce{sub {ital x}}CuO{sub 4{minus}{ital y}}, Nd{sub 2{minus}{ital x}}Ce{sub {ital x}}CuO{sub 4{minus}{ital y}}, and Sm{sub 2{minus}{ital x}}Ce{sub {ital x}}CuO{sub 4{minus}{ital y}} were investigated as a function of Ce concentration using Raman scattering at room temperature. The introduction of electrons by Ce doping significantly broadens the two-magnon peak in the {ital B}{sub 1{ital g}} mode, indicating that zone-boundary magnons become damped with increasing Ce concentration. The existence of broad spin-pair-excitation spectra in the {ital B}{sub 1{ital g}} and {ital B}{sub 2{ital g}} modes at {ital x}=0.15 suggests that the short-range spin fluctuations persist in these electron-doped superconductors. The energy of the spin-pair-excitation peak in Pr{sub 2{minus}{ital x}}Ce{sub {ital x}}CuO{sub 4{minus}{ital y}} is not affected by doping up to {ital x}=0.2. This is similar in behavior to the Sm{sub 2{minus}{ital x}}Ce{sub {ital x}}CuO{sub 4{minus}{ital y}} system up to {ital x}=0.17. The absence of softening of the short-wavelength magnons in these systems is in marked contrast to the magnon softening behavior in La{sub 2{minus}{ital x}}Sr{sub {ital x}}CuO{sub 4{minus}{ital y}}. The Raman spectra in Pr{sub 2{minus}{ital x}}Ce{sub {ital x}}CuO{sub 4{minus}{ital y}} make no distinction between the superconducting and the metallic regions. The highly damped magnetic-excitation spectra support the picture that the spin-spin correlation length in the present systems decreases gradually with increasing Ce concentration.

• OSTI ID: 5637402
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 43:4; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ANTIFERROMAGNETISM
CERIUM COMPOUNDS
CERIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL DOPING
HIGH-TC SUPERCONDUCTORS
MAGNETISM
MAGNONS
NEODYMIUM COMPOUNDS
NEODYMIUM OXIDES
OXIDES
OXYGEN COMPOUNDS
PRASEODYMIUM COMPOUNDS
PRASEODYMIUM OXIDES
QUASI PARTICLES
RAMAN SPECTRA
RARE EARTH COMPOUNDS
SAMARIUM COMPOUNDS
SAMARIUM OXIDES
SPECTRA
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS