Abstract
We have measured the spin susceptibility, , of the planes in the underdoped high superconductor, by electron spin resonance (ESR) in single crystals and aligned powders in fields up to 15.4 T. At low temperatures and high fields, is enhanced slightly in the orientation with respect to the orientation. The enhancement at ( ) at ( ) is small: approximately of , suggesting that the second critical field of superconductivity, , would not suppress the pseudogap. This work demonstrates the potential of high field ESR in single crystals for studying high superconductors.
- Received 15 February 2000
DOI:https://doi.org/10.1103/PhysRevLett.85.5627
©2000 American Physical Society