We conducted195Pt-nuclear magnetic resonance measurements on various-diameter Pt nanoparticles coated with polyvinylpyrrolidone in order to detect the quantum size effect and the discrete energy levels in the electron density of states, both of which were predicted by Kubo more than 50 years ago. We succeeded in separating the signals arising from the surface and interior regions and found that the nuclear spin-lattice relaxation rates in both regions show the metallic behavior at high temperatures. Surprisingly, the magnetic fluctuations in both regions exhibited anomalous behavior below the same temperature T∗, which points to a clear size dependence and is well scaled with δKubo. These results suggest that a size-tunable metal-insulator transition occurs in the Pt nanoparticles as a result of the Kubo effect.
@article{arxiv.2003.07585,
title = {NMR-based gap behavior related to the quantum size effect},
author = {Tomonori Okuno and Masahiro Manago and Shunsaku Kitagawa and Kenji Ishida and Kohei Kusada and Hiroshi Kitagawa},
journal= {arXiv preprint arXiv:2003.07585},
year = {2020}
}
Comments
11 pages, 10 figures, including supplemental materials, accepted for publication in Phys. Rev. B as a Rapid Communication