Novel ordered phases at low temperatures and dynamic phase transitions in the superconducting vortex system

2015 Fiscal Year Final Research Report

• Project/Area Number: 25287084
• 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: Okuma Satoshi 東京工業大学, 理工学研究科, 教授 (50194105)
• Co-Investigator(Renkei-kenkyūsha): KOKUBO Nobuhito 電気通信大学, 情報理工学研究科, 准教授 (80372340) ; ISHIDA Takekazu 大阪府立大学, 工学系研究科, 教授 (00159732)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 超伝導 / 渦糸 / 量子相転移 / 非平衡ダイナミクス / 動的相転移 / 超伝導絶縁体転移

Outline of Final Research Achievements

We have developed a measurement system for a mode-locking resonance with pulsed currents that generate much less heat (by three orders of magnitude) than the previous one, which enables to detect the flow of fast driven vortex lattices. By employing it at low temperatures down to 0.05 K, we successfully observe the dynamic quantum melting of driven lattice in the limit of zero pinning. Thus, we complete static vortex phase diagrams at nearly zero temperature as a function of applied field, namely, the phase diagrams of the field-induced quantum phase transition simultaneously in the absence and presence of pinning. Also, we have performed studies on the reversible-to-irreversible flow transition (RIT) and obtained the following new results: We acquire information on the vortex configuration in the vicinity of RIT. Also, we observe the critical behavior of RIT in the translational motion system where only the local ac shear due to strong random pinning is present.

Free Research Field

数物系科学