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Influence of randomness on the Mott transition in κ ‐(BEDT‐TTF) 2 X
Author(s) -
Sasaki T.,
Sano K.,
Sugawara H.,
Yoneyama N.,
Kobayashi N.
Publication year - 2012
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/pssb.201100614
Subject(s) - condensed matter physics , mott transition , anderson localization , weak localization , metal–insulator transition , hydrostatic pressure , fermi liquid theory , superconductivity , electron , electron localization function , organic superconductor , physics , mott insulator , electrical resistivity and conductivity , strongly correlated material , randomness , materials science , hubbard model , quantum mechanics , magnetoresistance , magnetic field , statistics , thermodynamics , mathematics
We present a detailed transport study in the organic superconductor κ ‐(BEDT‐TTF) 2 Cu[N(CN) 2 ]Br that is irradiated by X‐rays. Weak molecular disorder introduced by X‐ray irradiation induces the Anderson‐type localization insulating state from the strongly correlated metallic/superconducting state. The hydrostatic pressure to the localization insulator restores the metallic properties. These observations indicate that the stronger electron correlations upon approaching the Mott transition enhance Anderson‐type electron localization due to disorder introduced by X‐ray irradiation. In the metallic state with weak disorder or under pressure, the resistivity shows a T 2 dependence, which suggests that the dominant electron scattering comes from the electron–electron correlations of a Fermi‐liquid metal. The coefficient A of the T 2 term, however, seems not to follow the Fermi‐liquid theory fully as the origin of the T 2 dependence in a case of the disorder effect. Further studies of the competition and/or cooperation of the Mott and Anderson transitions close to the Mott critical point are important for understanding the critical behavior of the electrons in real materials.