Spin Polarization Measurements On Polycrystalline Strontium Ruthenates Using Point-Contact Andreev Reflection

Point-contact Andreev reflection (PCAR) measurements were made on bulk polycrystalline SrRu(0.8)Ti(0.2)O(3) and SrRu(0.92)O(3) samples to determine the transport. spin polarization. The parent compound SrRuO(3) undergoes ferromagnetic ordering at T(C) similar to 160 K with relatively high spin polarization (similar to 60%). For the SrRu(0.8)Ti(0.2)O(3) and SrRu(0.92)O(3) samples, a reduction in TC occurs. Moreover, our measurements indicate that the SrRu(0.8)Ti(0.2)O(3) system retains a high degree of spin polarization (P similar to 0.6), similar to the parent compound. However, due to the insulating nature of SrRu(0.92)O(3), the PCAR technique did not yield information on P. Instead, the data displayed nonlinear I-V consistent with the tunnelinglike spectra. (c) 2005 American Institute of Physics.