The Possible Mechanism of the Change of Carrier Types in SrRuO₃ Films

SrRuO₃ is widely used as a conduction layer for multilayer system, which exhibits a ferromagnetic transition around 165K. The SRO films were grown by a standard PLD system with a thickness of 180nm. The X-ray and Neutron scattering show the quality of the films is as good as a single crystal. The transport and magnetic measurement indicates a parallel-ferromagnetism transition at 155K. Hall measurements shows a clear hysteresis loops at low field region, the anomalous Hall effect, when the temperature is lower than the T_C. At high field region, corresponding to a normal Hall effect, the conduction carriers is found to be electron-like below T_C and hole-like above T_C. Since the Hall coefficients changes sign from negative to positive around T_C indicating the spin-split coupling strongly affects the local band structure. The split bands is simulated as a two-band model to describe the Hall measurement results. Two bands changes while magnetic coupling is introduced at low temperature.