New Features to Increase the Thermopower in Magnetic Semiconductors

In this paper thermopowerS, magnetothermopower ΔS/S were studied in single-crystal Sm(1-x)Srx MnO3 (0.15≤x≤0.3). It is known that these compounds consist of ferron-type ferromagnetic clusters in A-type antiferromagnetic matrix. A sharp increase of S and module of negative ΔS/S were discovered near Curie temperature TC, where they achieve giant values. So|ΔS/S|=94.5% in magnetic field 13.23 kOe. This means that thermopower is caused by presence of ferrons, as the value of the thermopower slumps with ferrons' destruction caused by magnetic field or heating over TC. Therefore thermopower in doped magnetic semiconductors is determined by level of doping and volume of the sample. So after dividing the sample in two parts thermopower of each part decreased proportionally the volume of the sample. Thus, in doped magnetic semiconductors the value of thermopower can be considerably increased by enlarging the volume of sample, the level of dopingand can be controlled by magnetic field.