Controlling wetting properties of 4He crystals and pioneering quantum tribology

2017 Fiscal Year Final Research Report

• Project/Area Number: 26287074
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Nomura Ryuji 東京工業大学, 理学院, 助教 (00323783)
• Co-Investigator(Kenkyū-buntansha): 奥田 雄一 東京工業大学, 理工学研究科, 教授 (50135670)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 量子固体 / 超流動 / トライボロジー / 摩擦 / 接触角 / 濡れ / Cassie-Baxter state / 結晶成長

Outline of Final Research Achievements

It was demonstrated that a 4He crystal can undergo motion on an oscillating plate as the result of employing an inchworm driving, a technique that is employed to impart motion, based on the difference between static and dynamic friction forces. However, the observed motion was quite different from the ordinary behavior of classical objects. The movement of these quantum crystals can be attributed to the anomalously quick crystal-superfluid transition, namely crystallization on one side and melting on the other, assisted by superflow induced during the oscillation.
It was demonstrated that controlling the contact angle of a 4He crystal in superfluid is possible on a rough wall. From the comparison of the contact angles and SEM image of the rough wall, the Cassie-Baxter state was likely to be realized on it; the 4He crystal had a direct contact with the protruding parts of the rough surface but superfluid was entrapped between the crystal and the hollow parts of the wall.

Free Research Field

低温物理学