Electronic properties in itinerant ferromagnet SrRu1−xTixO3

Abstract

Here, we study the electrical transport and specific heat in 4d based ferromagnetic material SrRuO3 and its Ti substituted SrRu1−xTixO3 series (x ⩽ 0.7). The SrRuO3 is a metal and shows itinerant ferromagnetism with transition temperature Tc ∼ 160 K. The nonmagnetic Ti4+ (3d0) 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 T2 dependence below Tc which though modifies to T3/2 dependence at low temperature. In Ti substituted samples, temperature range for T3/2 dependence extends to higher temperature. Interestingly, this T3/2 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.