The superconducting gap structure of nanocrystalline MgB2 is investigated by heat capacity measurements. It is shown that the larger σ-gap decreases as a consequence of defects and impurities introduced by the specifics of the high-energy ball milling synthesis process. This explains the reduction of the critical temperature. The smaller π-gap slightly increases as compared to bulk MgB2 indicating an enhanced interband scattering in the nanocrystalline samples.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering