Authors: George Rajna
One of the greatest mysteries in condensed matter physics is the exact relationship between charge order and superconductivity in cuprate superconductors.  Cuprates hold the record high superconducting temperature at ambient pressure so far, but understanding their superconducting mechanism remains one of the great challenges of physical sciences listed as one of 125 quests announced by Science.  Now, scientists at Tokyo Institute of Technology (Tokyo Tech), the University of Tokyo and Tohoku University report curious multi-state transitions of these superconductors in which they change from superconductor to special metal and then to insulator.  Researchers at the Zavoisky Physical-Technical Institute and the Southern Scientific Center of RAS, in Russia, have recently fabricated quasi-2-D superconductors at the interface between a ferroelectric Ba0.8Sr0.2TiO3 film and an insulating parent compound of La2CuO4.  Scientists seeking to understand the mechanism underlying superconductivity in "stripe-ordered" cuprates-copper-oxide materials with alternating areas of electric charge and magnetism-discovered an unusual metallic state when attempting to turn superconductivity off.  This discovery makes it clear that in order to understand the mechanism behind the enigmatic high temperature superconductivity of the cuprates, this exotic PDW state needs to be taken into account, and therefore opens a new frontier in cuprate research.  High-temperature (Tc) superconductivity typically develops from antiferromagnetic insulators, and superconductivity and ferromagnetism are always mutually exclusive.  Scientists at the U.S. Department of Energy's Ames Laboratory have developed a method to accurately measure the "exact edge" or onset at which a magnetic field enters a superconducting material.  TU Wien has now made a major advance towards achieving this goal and, at the same time, has furthered an understanding of why conventional materials only become superconducting at around-200°C  The emerging field of spintronics leverages electron spin and magnetization. 
Comments: 43 Pages.
[v1] 2019-08-17 02:17:18
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