Spin-singlet small bipolarons in Nb-doped BaTiO3.
The magnetic susceptibility and the electrical resistivity of n-type BaTi1-xNbxO3 have been measured over a wide temperature range. It is found that, for 0<x<0.2, dopant electrons form immobile spin-singlet small bipolarons with binding energy around 110 meV. For x=0.2, a maximum in the electrical resistivity around 15 K indicates a crossover from band to hopping transport of the charge carriers, a phenomenon expected but rarely observed in real polaronic systems.
Kolodiazhnyi
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ICYS, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan. koloditv@mcmaster.ca
Wimbush
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SC