Ferromagnetic quantum phase transition in Sr1-xCaxRuO3 thin films

The ferromagnetic (FM) quantum phase transition in the perovskite ruthenate Sr1-xCaxRuO3 is studied by low-temperature magnetization and electrical resistivity measurements on thin films. The films were grown epitaxially on SrTiO3 substrates using metalorganic aerosol deposition and characterized by X-ray diffraction and room temperature scanning tunneling microscopy. High residual resistivity ratios of 29 and 16 for x = 0 and 1, respectively, prove the high quality of the investigated samples. We observe a continuous suppression of the FM Curie temperature from T-C = 160 K at x = 0 towards T-C --> 0 at x(c) approximate to 0.8. The analysis of the electrical resistivity between 2 and 10 K reveals T-2 and T-3/2 behavior at x <= 0.6 and x >= 0.7, respectively. For undoped CaRuO3, the measurement has been extended down to 60 mK, revealing a crossover to T-2 behavior around 2 K, which suggests a Fermi-liquid ground state in this system. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim