Abstract
The magnetoelectronic properties of , which include giant magnetoresistance, are strongly dependent on the level of hole doping. The system evolves, with increasing , from a spin glass insulator to a metallic ferromagnet with a metal-insulator (MI) transition at . Nanoscale phase separation occurs in the insulating phase and persists, to some extent, into the just-metallic phase. The present experiments at 4.2 K have used nuclear magnetic resonance to investigate the transition from hopping dynamics for to Korringa-like ferromagnetic metal behavior for . A marked decrease in the spin-lattice relaxation rate is found in the vicinity of as the MI transition is crossed. This behavior is accounted for in terms of the evolution of the electronic structure and dynamics with cluster size.
- Received 15 July 2015
- Revised 30 November 2015
DOI:https://doi.org/10.1103/PhysRevB.93.024204
©2016 American Physical Society