Low-temperature specific heat of the high-T/sub c/ superconductors La/sub 1. 8/Sr/sub 0. 2/CuO/sub 4-//sub delta/ and RBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ (R = Y, Eu, Ho, Tm, and Yb)

Journal Article · Mon Feb 01 04:00:00 EST 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.37.1580· OSTI ID:5680316

Ferreira, J M; Lee, B W; Dalichaouch, Y; Torikachvili, M S; Yang, K N; Maple, M B

Low-temperature specific-heat measurements have been carried out between 0.5 and 30--50 K on the high-T/sub c/ copper oxide superconductors La/sub 1.8/Sr/sub 0.2/CuO/sub 4-//sub delta/ and RBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ (R = Y, Eu, Ho, Tm, and Yb). The specific heat of the La/sub 1.8/Sr/sub 0.2/CuO/sub 4-//sub delta/ and YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ compounds below T/sub c/ can be resolved into a contribution of the form C/sub e/(T) = ..gamma..'T with a finite ..gamma..' and a lattice contribution that consists of Debye and Einstein terms. Specific-heat data for the RBa/sub 3/Cu/sub 3/O/sub 7-//sub delta/ compounds with R = Ho, Tm, and Yb exhibit no features due to magnetic order above 0.5 K, but reveal electronic Schottky anomalies associated with crystalline electric field (CEF) splitting of the Hund's-rules ground-state multiplet of the R/sup 3+/ ions. The Schottky anomalies can be described by calculations based on tentative energy-level schemes for the Ho/sup 3+/, Tm/sup 3+/, and Yb/sup 3+/ ions in the CEF which are presented. Specific-heat data for the EuBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ compound, which can be separated into a ..gamma..'T term, a Debye contribution, and a low-temperature upturn, are consistent with a nonmagnetic J = 0 ground state for Eu/sup 3+/, as expected from Hund's rules.

• Research Organization: Department of Physics, University of California, San Diego, La Jolla, California 92093
• OSTI ID: 5680316
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 37:4; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
DATA
ENERGY LEVELS
EUROPIUM COMPOUNDS
EUROPIUM OXIDES
EXPERIMENTAL DATA
HOLMIUM COMPOUNDS
HOLMIUM OXIDES
INFORMATION
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
LOW TEMPERATURE
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SPECIFIC HEAT
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
THULIUM COMPOUNDS
THULIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
ULTRALOW TEMPERATURE
YTTERBIUM COMPOUNDS
YTTERBIUM OXIDES
YTTRIUM COMPOUNDS
YTTRIUM OXIDES