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Superconductor–Insulator Transitions in 2D: The Experimental Situation
Author(s) -
Marković N.,
Christiansen C.,
Mack A.,
Goldman A.M.
Publication year - 2000
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(200003)218:1<221::aid-pssb221>3.0.co;2-j
Subject(s) - condensed matter physics , superconductivity , phase diagram , insulator (electricity) , phase transition , materials science , quantum phase transition , magnetic field , critical exponent , physics , phase (matter) , quantum mechanics , optoelectronics
Superconductor–insulator (SI) transitions in ultrathin films have attracted significant attention over the last decade because of the possibility that they are quantum phase transitions. Magnetic field, film thickness, or carrier concentration can be used as control parameters. The bosonic pictures of these transitions proposed some years ago are only in qualitative agreement with experiment. In particular, the critical resistance appears not to be universal, and there are variations in the values of critical exponents. It has been concluded that in real films fermionic degrees of freedom must be taken into account. There are also indications that the phase diagram may include a significant metallic phase separating the superconducting and insulating phases, and that the transition may have a significant percolative aspect. The experimental situation will be broadly reviewed with attention paid to issues relating to materials and measurements.