Abnormal positive magnetoresistance in a weak magnetic field in Ge:As on the metallic side close to the metal–insulator transition

✍ Scribed by Rolf Rentzsch; Alexander N. Ionov

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 165 KB
• Volume: 359-361
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2005.01.458

✦ Synopsis

We observed abnormal positive magnetoresistance (apm) in Ge at relatively small magnetic fields and low temperature (down to 30 mK) which was very different from the positive magnetoresistance connected with the shrinkage effect and also different to the negative magnetoresistance which was obtained in bulk GaAs for control purposes. Experiments were performed on isotropic-engineered bulk Ge with high homogeneous impurity distribution obtained by neutron-transmutation doping on the metallic side of metal-insulator transition (MIT) very close to N c . The apm was saturated in magnetic fields in a range of 0.4-0.6 T. We consider that the resistivity of our system is influenced by electron-phonon interactions which form superconducting fluctuations (Maki-Thomson correction to the conductivity) similar to Bose-Einstein condensation for barely free electrons with small Fermi energy. In a small magnetic field, these fluctuations are suppressed, resulting in an apm.