Electronic properties in itinerant ferromagnet SrRu_1-x Ti _x O₃

Here, we study the electrical transport and specific heat in 4d based ferromagnetic material SrRuO₃ and its Ti substituted SrRu_1-x Ti _x O₃ series (x ⩽ 0.7). The SrRuO₃ is a metal and shows itinerant ferromagnetism with transition temperature T _c ∼ 160 K. The nonmagnetic Ti⁴⁺ (3d ⁰) substitution would not only weaken the active Ru-O-Ru channel but is also expected to tune the electronic density and electron correlation effect. A metal to insulator transition has been observed around x ∼ 0.4. The nature of charge transport in paramagnetic-metallic state (x ⩽ 0.4) and in insulating state (x > 0.4) follows modified Mott's variable range hopping model. In ferromagnetic-metallic state, resistivity shows a T ² dependence below T _c which though modifies to T ^3/2 dependence at low temperature. In Ti substituted samples, temperature range for T ^3/2 dependence extends to higher temperature. Interestingly, this T ^3/2 dependence dominates in whole ferromagnetic regime in presence of magnetic field. This evolution of electronic transport behavior can be explained within the framework of Fermi liquid theory and electron-magnon scattering mechanism. The negative magnetoresistance exhibits a hysteresis and a crossover between negative and positive value with magnetic field which is connected with magnetic behavior in series. The decreasing electronic coefficient of specific heat with x supports the increasing insulating behavior in present series. We calculate a high Kadowaki-Woods ratio (x ⩽ 0.3) for SrRuO₃ which increases with substitution concentration. This signifies an increasing electronic correlation effect with substitution concentration.