The boil-off effect and negative magnetoresistance in p-Hg1−xMnxTe1−ySey

Abstract

The galvanomagnetic effects in zero- and narrow-gap semimagnetic semiconductors Hg1−xMnxTe1−ySey with x=0.03÷0.11, y=0.01÷0.10 (−150≤Eg≤190)meV and acceptor concentrations 5.5×1016≤Na≤4.3×1018cm−3 were investigated. In the magnetic fields H=(5÷50)kOe and T=(1.3÷4.2)K an essential (up to 450 times) increase of the hole concentration p=1/cR was observed. This increase is accompanied by a fall both of longitudinal and transverse magnetoresistances. We suppose that a “boil-off” (opposite to freeze-out) of holes is the consequence of the existence of bound magnetic polaron states at H=0 and of the carrier delocalization due to the gradual destruction of those states in external magnetic field. This boil-off effect is enhanced essentially as it should be with a rise of the Mn content.