Magnetic versus nonmagnetic ion substitution effects in gapless semiconductor PbPdO2

PbPdO2 is a gapless semiconductor, of which the physical properties are easily tuned by external parameters such as temperature, magnetic field, and chemical doping. We have studied the physical properties tuned by magnetic and nonmagnetic ion substitutions. When Pd in PbPdO2 is substituted by Zn, that is, divalent and nonmagnetic with 3d(10) (S = 0), the electrical resistivity decreases and the magnetic properties are not changed to remain diamagnetic. However, by substituting Cu2+ (3d(9)) with S = 1/2, the electrical resistivity increases and the magnetization shows paramagnetic behavior. Another noticeable feature in the magnetic versus nonmagnetic ion substitution is found in the magneto-transport data. The magnetoresistance for PbPd0.9Cu0.1O2 is positive, compared with the negative behavior for PbPd0.9Zn0.1O2. These results propose that chemical dopants play an important role in optimizing the tunability of the physical properties of gapless semiconductors. (C) 2015 AIP Publishing LLC.