skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Search for: All records

Creators/Authors contains: "Delgado, S"

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. We report results of magnetization and 19F NMR measurements in the normal state of as-grown vacuum-annealed LaO0.5⁒F0.5⁑BiS2. The magnetization is dominated by a temperature-independent diamagnetic component and a field- and temperature-dependent paramagnetic contribution π‘€πœ‡β‘(𝐻,𝑇) from a ∼1000 ppm concentration of local moments, an order of magnitude higher than can be accounted for by measured rare-earth impurity concentrations. π‘€πœ‡β‘(𝐻,𝑇) can be fit by the Brillouin function 𝐡𝐽⁑(π‘₯) or, perhaps more realistically, a two-level tanh⁑(π‘₯) model for magnetic Bi 6⁒𝑝 ions in defect crystal fields. Both fits require a phenomenological Curie-Weiss argument π‘₯=πœ‡eff⁒𝐻⁑/(𝑇+π‘‡π‘Š), π‘‡π‘Šβ‰ˆ1.7 K. There is no evidence for magnetic order down to 2 K, and the origin of π‘‡π‘Š is not clear. 19F frequency shifts, linewidths, and spin-lattice relaxation rates are consistent with purely dipolar 19F/defect-spin interactions. The defect-spin correlation time πœπ‘β‘(𝑇) obtained from 19F spin-lattice relaxation rates obeys the Korringa relation πœπ‘β’π‘‡=const, indicating the relaxation is dominated by conduction-band fluctuations. 
    more » « less
    Free, publicly-accessible full text available December 1, 2025