Specific Heat of (Sr--Ca)RuO₃

抄録

The specific heat of (Sr--Ca)RuO₃ system was measured by an adiabatic method utilizing a heat-pulse technique. The values of electronic specific heat coefficient γ change from 30, mJ/molK² for SrRuO₃ to 82, mJ/molK² for CaRuO₃ through a maximum value of about 100, mJ/molK² for Sr_0.2Ca_0.8RuO₃. A strong upturn in the C/T vs T² curve at low temperatures has been observed for paramagnetic Sr_0.2Ca_0.8RuO₃ and CaRuO₃. This behavior is quantitatively explained by the spin-fluctuation theory of the itinerant-electron magnetism, suggesting that this system possibly changes from intermediate itinerant ferromagnet of SrRuO₃, through weakly itinerant ferromagnet, to nearly ferromagnetic metal of CaRuO₃.