The influence of A site disorder on the magnetic and transport properties of Pr0.6R0.1Sr0.3MnO3 (R = Tb, Y, Ho, and Er) polycrystalline samples is analyzed within the context of percolative transport and the existence of the Griffiths phase. The temperature dependence of the average spin moment at the hopping sites and the fraction of metallic clusters bear signatures of the onset of the Griffiths phase. Our analysis suggests that the paramagnetic phase comprises of insulating correlated spin clusters that coexist with ferromagnetic metallic clusters and paramagnetic spins. This coexistence was found to be sensitive to the A-site disorder.

Sankaranarayanan V

Department Of Physics

Mamidanna Sri Ramachandra Rao

Erbium

Holmium

Manganese oxide

Perovskite

Terbium

yttrium

article

crystal

Magnetic field

Magnetism

neutron scattering

phase transition

scanning tunneling microscopy

temperature dependence

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IIT Madras

Physical Review B - Condensed Matter and Materials Physics

Temperature variation of electrical resistivity, thermopower and electron spin resonance measurements have been carried out in Pr (1-x)SrxMnO3 (x = 0.2, 0.26 and 0.3) in order to study the influence of carrier concentration on the formation of spin clusters in the paramagnetic state. Activation energies obtained from resistivity and thermopower was seen to behave in the opposite trend to that obtained from ESR linewidth and intensity with respect to variation in 'x', the carrier concentration, implying that the origin of these energies are different from each other. It is seen that spin clusters exist in the paramagnetic state even in a ferromagnetic insulating composition namely x = 0.2, where the double exchange strength is the weakest. © 2007 Elsevier B.V. All rights reserved.

Journal of Alloys and Compounds

Electrical resistivity, thermoelectric power and electron spin resonance studies on Pr(1-x)SrxMnO3 (x = 0.2, 0.26 and 0.3)

In this paper, we report the influence of the disorder on the magnetization and magnetoresistance in Pr0.6 R0.1 Sr0.3 MnO3 (R = Tb, Y, Ho and Er) manganites at high and low temperatures. At high temperatures, it is seen that both these properties are governed by the lowering of average A-site radii and increase in variance of the A-site disorder while at low temperatures by the rare earth ion coupling with that of Mn sublattice. The rare earth sublattice was found to order at a temperature very similar to that of corresponding rare earth manganate even though their concentrations were small. The magnetoresistance was found to scale with both the lowering of average A-site radii and increase in variance of the A-site disorder while at low temperatures was found to be independent of variance but rather depends on whether the dopant ion is magnetic or non magnetic. This behaviour was attributed to the competition that exists between double exchange and Jahn-Teller mechanisms which govern the physics of these systems. © 2006 Elsevier B.V. All rights reserved.

Influence of disorder on the low and high temperature magnetization and magnetoresistance in Pr0.6 R0.1 Sr0.3 MnO3 (R = Tb, Y, Ho and Er) manganite

Transport properties of mixed-valence manganites of the type (La0.7-xRx)Ca0.3MnO3 where R = Ho (magnetic) and Y (nonmagnetic) have been investigated above the ferromagnetic transition temperature (Tc). It is interesting to see that the Ho-doped compounds have less resistivity compared to the Y-doped compounds, although Ho and Y ions have almost the same ionic radii and hence lattice strain effect would be the same in both the cases. The internal magnetic field of Ho (μeffHo= 10.5μB) is found to be responsible for this decrease in resistivity in Ho-doped compounds. Coupling of Ho magnetic moment to that of Mn has been confirmed by magnetization measurements. The resistivity data above Tc fit well to the magnetic localization model proposed by Viret et al. [Phys. Rev. B 55, 8067 (1997); Phys. Rev. Lett. 75, 3910 (1995)] and the localization lengths thus obtained are reasonable. The localization lengths of the Ho-doped compounds are greater than that of Y-doped compounds of the same composition indicating that the coupling of the Ho moment with that of the Mn moments is responsible for this effect.

Magnetotransport studies and mechanism of Ho- and Y-doped La0.7Ca0.3MnO3

Discrete & Continuous Dynamical Systems - A

On density of infinite subsets I

Physical Review Letters

Colossal Magnetoresistance is a Griffiths Singularity

Physical Review B

Common features of nanoscale structural correlations in magnetoresistive manganites with a ferromagnetic low-temperature state

Physics Reports

Colossal magnetoresistant materials: the key role of phase separation

A-site-disorder-dependent percolative transport and Griffiths phase in doped manganites

Journal	Data powered by TypesetPhysical Review B - Condensed Matter and Materials Physics
Publisher	Data powered by TypesetAmerican Physical Society
ISSN	10980121
Open Access	No