The Magnetic Properties of the Cuprate Superconductors
Abstract
The author reports on a study of the magnetic properties of the cuprate superconductors in both the normal and superconducting states. The magnetic properties are studied by making comparison to the results of nuclear magnetic resonance experiments. The author gives a simplification of the method used to calculate the nuclear magnetic resonance spin-echo decay time for these materials. Experiments on the YBa _2Cu_3O_7, YBa_2Cu _3O_{6.63}, YBa _2Cu_4O_8, Y_ {1-x}Pr_{x}Ba_2Cu_3O _7, and La_{1.85}Sr _{0.15}CuO_4 materials are analyzed. The compatibility of an electron spin susceptibility that has correlations incommensurate with the lattice as measured in neutron scattering experiments is found to be in conflict with the measured nuclear magnetic relaxation rates. The author reports on calculations of the electron spin susceptibility for the superconducting state of YBa _2Cu_3O_7 using a band structure with nearest and next nearest neighbor hopping, a momentum dependent spin-spin interaction and a superconducting gap with d_{x^{2}-y^ {2}} symmetry. The calculated nuclear magnetic relaxation rates and Knight shift agree favorably with experiment. This work provides further evidence for a d_{x^{2}-y^ {2}} pairing state and demonstrates that antiferromagnetic correlations persist in the superconducting state.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- January 1994
- Bibcode:
- 1994PhDT........27T
- Keywords:
-
- YTTRIUM BARIUM COPPER OXIDE;
- Physics: Condensed Matter