Anomalous Transport Phenomena of Photoelectrons in the Ferromagnetic Semiconductor EuO

概要

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Anomalous transport phenomena of photoelectrons in pure Eu0 crystals have beenstudied over the temperature range from T = 4.2 K to 80 K and in the magnetic fields upto H= 50 k0e by using a fast-pulse technique with blocking electrodes. The Redfieldgeometry was used to determine directly the value of Hall mobility of photocarriers, p..Anomalous behaviours of photoconductivity such as an abrupt increase below theCurie temperature T.=69.5 K and a large negative-magnetoresistance effect around T.were observed. The value of jt. has been measured as a function of both thetemperature and the magnetic field. It was directly found that the value of jt. varieswith H around 7'.; the p.-value at I=63.5 K increases from 90 cm'/V. sec at #=0 to160 cm'/V. sec at H= 15 kOe. Thus, the anomalous transport phenomema in pure Eu0crystals around T. have been experimentally confirmed, for the first time, to be mainlydue to the mobility change. Experimental results are discussed in terms of the transporttheory based on the wide band scheme and the spin disorder scattering due to the s-fexchange interaction.
社団法人日本物理学会の論文
1977-12-15