Ge film thermometers at ultralow temperatures in high magnetic fields

The conduction mechanisms and effect of magnetic field for Ge-film thermometers in the 25 mK to 4.2 K temperature range and magnetic fields up to 6 T are studied. At low temperatures, the variable-range hopping conductivity prevails. At temperatures below 0.3 K, a gigantic negative magneto-resistanc...

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Bibliographic Details
Published in:Physica. B, Condensed matter Condensed matter, 2000-07, Vol.284, p.1996-1997
Main Authors: Mitin, Vadim, McFarland, John, Ihas, Gary G, Dugaev, Vitalii
Format: Article
Language:English
Subjects:
Heavily doped semiconductors
Localization
Magneto-resistance
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Summary:The conduction mechanisms and effect of magnetic field for Ge-film thermometers in the 25 mK to 4.2 K temperature range and magnetic fields up to 6 T are studied. At low temperatures, the variable-range hopping conductivity prevails. At temperatures below 0.3 K, a gigantic negative magneto-resistance (up to 100%) is observed. The temperature dependence of resistance and magneto-resistance shows that localization behavior near the mobility edge exists. To explain experimental results, we adopt a phenomenological model based on variable-range hopping below the mobility edge. We also use a scaling theory of localization with a localization length depending on the mobility edge location.
ISSN:0921-4526
1873-2135
DOI:10.1016/S0921-4526(99)02756-8