The measured positive and negative magnetoresistance for n-type germanium at room temperature

Magnetoresistance (MR) for n-type germanium wafers by in-line-four-terminal method at room temperature are explored. Conspicuously, the variation of the measured MR as a function of applied current and voltage-terminal separation is observed. With a further increase of applied current, the measured MR initially increases, passes through a peak value at a certain current and then finally decreases. The measured MR increases with an increase of the value of voltage-terminal separation. The most important outcome of this study is the observation of negative MR for the smallest voltage-terminal separation of 2 mu m, and the sign change of the measured MR can be achieved by magnetic fields. These interesting results may lead to an alternative approach to future magneto-electronic devices.