Dependence of Magnetization on Temperature, Magnetoresistance Effect and Magnetic Phase Diagram for the Layered Gd5Ge4 Compound

The dependence of dc magnetization and electrical transport on temperature were systemically studied for the layered Gd₅Ge₄ compound. A complex coexistence behavior of ferromagnetism (FM) with antiferromagnetism (AFM) phase and significant magnetoresistance effect were found under the inducement by the applied magnetic field. The results show an unusual magnetoresistance (MR) effect with opposite behavior at the high and low temperatures, which is positive at high temperature region and negative at low temperature region for the layered Gd₅Ge₄ alloy. And its MR maximum is close to 50%, which can be a very large numerical value e.g. for giant magnetoresistance (GMR) materials. From the magnetization loop under different temperatures, also a magnetization step behavior was found below ∼6.2 K. The results proved an existence of reentrance AFM phase at low temperature. From experimental data, also the magnetic phase diagram is obtained. This kind of complex magnetization is analyzed and discussed in the frame of phase separation. The experimental results opened also the possibility of application of the layered Gd₅Ge₄ compound in the fields of information record and sensor technique.