Magnetic Phase Transition and Variable Range Hopping Conduction of Y1-xSrxCoO3-delta

Abstract

The structural, magnetic, and electric properties of perovskite Y1−xSrxCoO 3−δ have been investigated systematically over the 0.6 ≤ x ≤ 0.9 range of doping. The refinements of X-ray powder diffraction (XRD) patterns at room temperature indicates that the investigated samples show a unit cell of about 2 × 2 × 4 simple perovskite cubes with I4/mmm group symmetry. An antiferromagnetic (AFM) phase is observed for a Sr doping of 0.60 ≤ x < 0.775. With a further increase of Sr content, 0.775 ≤ x ≤ 0.90, a mixture of AFM and ferromagnetic clusters may exist. No metallic behavior is observed for samples investigated in ambient conditions. The resistivity (ρ) data can be described using a three-dimensional variable range hopping (VRH) model. The density of states in the vicinity of the Fermi level for all compositions can be roughly estimated by fitting the temperature dependence of the resistivity.

Microstructure and electrical conductivity of (Y, Sr)CoO 3-δ thin films tuned by the film-growth temperature

“…It can be seen that the resistivity of these films increases exponentially with decreasing temperature in the measurement range from 300 to 95 K, which indicates that both films have semiconductor behavior. In comparison with the single-phase YSCO films, the resistivity of the composite films decreases roughly by a factor of four over the entire temperature range of 95−300 K. It is noted that the three dimensional variable range hopping (VRH) conduction model [33] has been applied to understand the conductivity of the YSCO bulk samples [19,21,34]. Similarly, the temperature dependence M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 6 of resistivity ρ(T) is also fitted by Mott's VRH model for our films.…”

Effect of Er substitution on ultrasonic anomaly in Dy0.5−xErxBa0.5CoO3 cobaltates

“…It is known that, Co 3+ ion in an octahedral symmetry can exhibit either low-spin (LS) (S = 0, t 6 2g e 0 g ), intermediate-spin (IS) (S = 1, t 5 2g e 1 g ) or high-spin (HS) HS (S = 2, t 4 2g e 2 g ) states depending on the Hund's rule exchange energy and the crystal field splitting effect, in contrast to mixed valence manganites where both of Mn 3+ (S = 2, t 3 2g e 1 g ) and Mn 4+ (S = 3/2, t 3 2g e 0 g ) are always in the HS states. As such, the Co 3+ ion may be in one of the spin states depending on which state is energetically more favorable for a particular situation [9].…”