DC Hall and infrared Hall effects in strontium ruthenite and calcium ruthenite

We measured the Hall angle thetaH of itinerant ferromagnet SrRuO3 and paramagnet CaRuO3 as a function of temperature (10K-200K) by using both DC and infrared techniques. The infrared Hall measurements were with DC Hall measurements to help us study extrinsic and intrinsic properties of the samples. CaxSr1-xO3(CSRO) compounds are strong electron-correlated materials, their unconventional Hall effect behaviors inspires us to learn and discuss the sign change of theta H as a function of temperature. In SrRuO3, the sign change of the DC Hall angle thetaH occurs near 140K from electron to hole like behavior as the temperature is increased. In CaRuO3, the DC thetaH smoothly changes sign from low temperature to high temperature crossing zero at 50K. We studied the frequency dependence of thetaH for both samples in the 100-400 meV energy range. In SrRuO3, the magnitude and temperature dependence of the infrared thetaH below 200 meV is very similar to that of the DC thetaH. Above 200 meV, the infrared theta H in SrRuO3 has same temperature dependence as the magnetic susceptibility. Unlike SrRuO3, the infrared thetaH for CaRuO3 displays the same temperature dependence as the magnetic susceptibility for all the measured infrared frequencies, showing no sign changes.