Investigation of YBa sub 2 Cu sub 3 O sub 7 by NMR and construction of an ultralow-temperature cryostat

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:7033795

Lovellette, M N

The author reports investigation by {sup 63}Cu NMR and NQR on the high-temperature superconductor YBa{sub 2}Cu{sub 3}O{sub 7}. The decay of the magnetization observed following an inversion of the Cu spin system is found to be nonexponential. The spin-lattice relaxation rate observed by NMR is not affected by the onset of superconductivity, and throughout the temperature range of 5 to 150 K is only weakly temperature-dependent. However, the NQR spin-lattice relaxation rate drops dramatically with decreasing temperature in the superconducting state. This suggests that different relaxation mechanism are functioning in zero field as observed by NQR and high field as observed by NMR. The NMR spin-lattice relaxation can be explained by the presence of a dilute fluctuating spin system which orders at a temperature of approximately 1 K. The concentration of spins found by NMR techniques, 0.67 {plus minus} 0.25 {times} 10{sup 21} spins/cm{sup 3} is in good agreement with the concentration determined by dc susceptibility measurements. The design and construction of a cryostat to conduct high-resolution NMR measurements on {sup 3}He-B is described.

• Research Organization: Northwestern Univ., Evanston, IL (USA)
• OSTI ID: 7033795
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM COMPOUNDS
CUPRATES
COPPER 63
NUCLEAR MAGNETIC RESONANCE
NUCLEAR QUADRUPOLE RESONANCE
COPPER COMPOUNDS
CRYOSTATS
DESIGN
SUPERCONDUCTORS
SPIN-LATTICE RELAXATION
YTTRIUM COMPOUNDS
HELIUM 3
TEMPERATURE DEPENDENCE
ALKALINE EARTH METAL COMPOUNDS
CONTROL EQUIPMENT
COPPER ISOTOPES
EQUIPMENT
EVEN-ODD NUCLEI
HELIUM ISOTOPES
INTERMEDIATE MASS NUCLEI
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
RELAXATION
RESONANCE
STABLE ISOTOPES
THERMOSTATS
TRANSITION ELEMENT COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties