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Effect of Spin‐Glass Ordering on Conduction in a‐Si 1— c Mn c near the Metal–Insulator Transition
Author(s) -
Yakimov A. I.,
Dvurechenskii A. V.,
Adkins C. J.
Publication year - 1998
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(199801)205:1<299::aid-pssb299>3.0.co;2-0
Subject(s) - condensed matter physics , conductivity , impurity , activation energy , magnetoresistance , materials science , thermal conduction , amorphous solid , variable range hopping , metal–insulator transition , electrical resistivity and conductivity , metal , spin glass , transition temperature , atmospheric temperature range , magnetic field , chemistry , thermodynamics , physics , crystallography , superconductivity , metallurgy , organic chemistry , quantum mechanics , composite material
The electrical conductivity and magnetoresistance of amorphous Si films implanted by Mn ions up to a concentration of 22 at% are investigated near the metal–insulator transition (MIT). We find that there is a characteristic temperature T SG = 6 to 20 K (dependent on the Mn concentration) which separates two different conductivity behaviours. As temperature is reduced below T SG on the insulating side of the MIT, the conductivity mechanism is found to change from variable‐range hopping to conductivity with constant activation energy Δ E which decreases linearly in a magnetic field. The activation energy of hopping determined from the data above T SG , on approaching T SG , turns out to be smaller than Δ E . In the metallic regime at T < T SG , we observe a shift of the MIT towards higher impurity concentration in respect with that determined from the data at T > T SG . The low‐temperature anomalies are ascribed to the spin‐glass transition caused by d–d interaction between Mn atoms.