From the 63Cu Knight shift and the nuclear spin-lattice relaxation rate under magnetic fields from zero up to 28 T in the underdoped (U) YBa2Cu4O8 and the slightly overdoped (O) TlSr2CaCu2O6.8, we find that the spin-gap (pseudogap) behaviors show contrasting response to magnetic fields in the U and O compounds. In the O compound, the spin-gap is strongly field dependent and can be accounted for by the superconducting fluctuation effects, but that in the U compound shows no field dependence. The implication is discussed.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics