SPONTANEOUS SPIN POLARIZATION AND ELECTRONIC STATES IN PLATINUM NANO-PARTICLE

摘要

Superconductivity of bulk platinum metal has not been observed down to a few μK. However, the superconductivity is observed on compacted platinum powder sample at mK temperature range. The grain size of the compacted powder is in the micron size range. This observation shows that the role of the granular characteristics is quite important in such an exotic superconductivity and the origin is related to the characteristics of the fine particles. However, the diameter size dependency of the electronic characteristics of the fine particles and surface effect are not so clear till now. Especially it is considered that the surface effect is closely related to the granular state in the compacted powder. Despite the importance of the cohesion effect in the gathering of fine particles, basic properties of each Pt fine-particle should be investigated to reveal the origin of the superconductivity. Particularly, to understand the surface characteristics is the indispensable procedures. When the diameter of a fine particle is reduced to the nano order range, special magnetic quantum effect appears. Although such a magnetic quantum effect is considered to be unfavorable to the superconductivity, investigations of the nano order Pt particle (Pt nano-particle) are still important to make clear the quantum effect of surface and inside Because the role of the surface is relatively large in nano-particles. Here we will investigate the magnetic and electronic quantum effects in Pt nano-particles and their surface characteristics.