Magnetic-field-induced electron localisation in narrow-gap semimagnetic Hg1−xMnxTe

In order to shed some light on the controversy concerning the nature of the field-induced localisation in narrow-gap n-Hg1-xCdxTe, the authors have performed magnetoresistance and Hall effect measurements on n-Hg1-xMnxTe up to 140 kOe and down to 30 mK. For magnetic fields H below 50 kOe the role of the quantum corrections to the conductivity tensor components is pointed out. The strong and temperature-dependent positive magnetoresistance which is observed for H>50 kOe can be interpreted as the field-induced Anderson localisation, driven presumably by disorder-modified electron-electron interaction in the spin-polarised band. In still higher fields, however, the magnetoresistance changes sign, a behaviour that is not well understood but may follow from the presence of accumulation layers at small-angle grain boundaries.