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This book presents experimental studies of nonequilibrium phase transitions induced by ac and dc forces in collectively interacting systems-a superconducting vortex system with random pinning. It first shows that a phase transition from reversible to irreversible flow occurs by increasing vortex density as well as amplitude of ac shear, which is indicative of the universality of the reversible-irreversible transition. Two distinct flow regimes are also found in the reversible phase. Next, the book presents new methods for dc driven experiments-transverse mode-locking and transverse current-voltage measurements-and provides convincing evidence of the second-order dynamical transition from disordered plastic to anisotropically ordered smectic flow. Lastly it reports on the first experimental demonstration of the Kibble-Zurek mechanism for the nonequilibrium phase transition.
The experimental results indicate that both the reversible-irreversible transition and the dynamical ordering transition belong to the directed percolation universality class which is one of the fundamental classes of nonequilibrium phase transitions. Hence, the findings will be generalized to other nonequilibrium systems and stimulate research on nonequilibrium physics.
List of contents
Experimental.- Critical behavior of RIT driven by particle density as well as shear amplitude.- Moving smectic phase and transverse mode locking in driven vortex matter.- Evidence of second-order transition and critical scaling for the dynamical ordering transition.- Kibble-Zurek mechanism for the dynamical ordering transition.- Conclusions.
About the author
Shun Maegochi is an experimentalist in condensed matter and nonequilibrium physics. His research interests include vortex physics, rheology and nonequilibrium phase transitions. To explore these research topics, he selected a superconducting vortex system as a suitable platform of physics system and developed several transport measurements.
At Tokyo Institute of Technology, he studied the collective dynamics of driven vortex matters in amorphous superconducting films under the supervision of Professor Satoshi Okuma, and received his B.S., M.S., and Ph.D. in science from Tokyo Institute of Technology in 2018, 2020 and 2023, respectively. He currently works as a specialist at Hitachi, Ltd. on design and development of superconducting equipment.
