Effect ofA-site cation size mismatch on charge ordering and colossal magnetoresistance properties of perovskite manganites

In this study, nanosized La1-xCaxFeO3 (0.00≤x≤0.40) compounds prepared via sol-gel method followed by heat treatment at 1100oC for 24 hours are studied. Crystal structure, microstructure, surface morphology and temperature-dependent resistivity of the samples are investigated. TEM investigation reveals nanoparticles with an average size of 35nm produced from the sol-gel process. The crystal structure of the compounds belongs to an orthorhombically distorted perovskite structure with Pbnm space group. Lattice distortion and cation size mismatch increase with an increase in Ca and particle and grain growth are suppressed by Ca doping. Electrical conduction is explained via thermally activated hopping of small polarons. Unit cell volume, charge ordering temperature, and activation energy for small polarons decrease linearly with an increase in cation size mismatch. Room temperature resistivity decreases with Ca doping and gets its minimum value for 30% Ca at which the orthorhombic distortion is maximum.

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Cation size mismatch effect in (La1-yREy)1.4Ca1.6Mn2O7 perovskite manganites

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2019.05.079 ◽

2019 ◽

Vol 797 ◽

pp. 471-476 ◽

Cited By ~ 2

Author(s):

N. Soylu Koc ◽

S.P. Altintas ◽

N. Mahamdioua ◽

C. Terzioglu

Keyword(s):

Perovskite Manganites ◽

Size Mismatch ◽

Cation Size ◽

Mismatch Effect

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Investigation of Lattice Effects in Rare Earth Manganites by 18O-isotope Exchange

Australian Journal of Physics ◽

10.1071/p98056 ◽

1999 ◽

Vol 52 (2) ◽

pp. 235 ◽

Cited By ~ 4

Author(s):

R. Mahesh ◽

M. Itoh

Keyword(s):

Rare Earth ◽

Colossal Magnetoresistance ◽

Charge Ordering ◽

Perovskite Manganites ◽

Lattice Effects ◽

Jahn Teller ◽

18O Isotope ◽

Ionic Size ◽

Rare Earth Manganites ◽

A Site

The strong coupling between the electron spin and lattice arising from the Jahn-Teller effect of manganese ions plays an important role in the mechanism of colossal magnetoresistance and related properties of the rare earth manganites. The lattice effects in this class of oxides have been extensively studied through the application of hydrostatic as well as chemical pressures and magnetic fields. The recently observed giant 18O isotope effect provides direct evidence for the formation of lattice polarons in manganites. Here we report the preliminary results of our investigations on a variety of normal as well as 18O isotope-exchanged perovskite manganites exhibiting colossal magnetoresistance and charge ordering. The observed isotope shift of Tc as well as that of Tco is correlated with the key parameters controlling the lattice such as the Mn 3+ content, the average ionic radius of the A-site cation ⟨rA⟩ , and the A-site ionic size disorder σ2 .

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Effect of the Grain Size on the Magnetic Phase Separation in La0.8Sr0.2MnO3 by Magnetic Force Microscopy

Microscopy and Microanalysis ◽

10.1017/s1431927612013165 ◽

2012 ◽

Vol 18 (S5) ◽

pp. 101-102

Author(s):

P. De Sousa ◽

N. Panwar ◽

I. Bdikin ◽

A. L. Kholkin ◽

C. M. Fernandes ◽

...

Keyword(s):

Grain Size ◽

Phase Separation ◽

Colossal Magnetoresistance ◽

Room Temperature ◽

Magnetic Phase ◽

Magnetic Domain ◽

Charge Ordering ◽

Perovskite Manganites ◽

Fundamental Study ◽

Metallic Clusters

Perovskite manganites have been the focus of worldwide research during the last two decades because of the observation of colossal magnetoresistance (CMR) effect. These materials have potential applications in magnetic field sensors, spin filters, infrared bolometers and cathodes for solid oxide fuel cells. Such manganites are also important from the fundamental study viewpoint as they offer interplay among various degrees of freedom viz. spin, lattice and charge ordering. Moreover, phase separation may occur in manganites with low concentration of the dopant. In such scenario, ferromagnetic metallic clusters are embedded in antiferromagnetic insulating matrix. The fraction of these magnetic phases may vary from the nano- to micro-scale. With higher dopant concentration, the percolation of these magnetic metallic clusters leads to the apparent CMR effect. In this study we focus our attention to the low doped La0.8Sr0.2MnO3 (LSMO) manganite and investigate the possible magnetic phase separation and effect of variation in grain size on the magnetic domain size. La0.8Sr0.2MnO3 possesses Curie temperature (TC) higher than room temperature, therefore the material is supposed to be in the magnetic state at room temperature.

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Effect of A-site cation size mismatch on charge ordering behavior in (La1−xYx)0.5(Ca1−ySry)0.5MnO3

Journal of Applied Physics ◽

10.1063/1.1376402 ◽

2001 ◽

Vol 90 (1) ◽

pp. 488-492 ◽

Cited By ~ 10

Author(s):

Y. Q. Wang ◽

Ian Maclaren ◽

X. F. Duan ◽

Z. H. Wang ◽

B. G. Shen

Keyword(s):

Charge Ordering ◽

Size Mismatch ◽

A Site ◽

Cation Size

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SPIN AND ORBITAL PHYSICS IN MANGANITES

International Journal of Modern Physics B ◽

10.1142/s0217979201006501 ◽

2001 ◽

Vol 15 (19n20) ◽

pp. 2727-2745 ◽

Cited By ~ 1

Author(s):

R. Y. GU ◽

Z. D. WANG

Keyword(s):

Colossal Magnetoresistance ◽

Lattice Distortion ◽

Double Exchange ◽

Charge Ordering ◽

Perovskite Manganites ◽

Electronic Correlation ◽

Strong Electronic Correlation ◽

Jahn Teller ◽

Orbital Physics ◽

Magnetic Orbital

The spin and orbital physics in perovskite manganites is briefly reviewed. Perovskite manganites are well known as the materials exhibiting colossal magnetoresistance (CMR), whose mechanism is based on the double exchange (DE) interaction, in which the electron hopping is connected with the spin configurations of the manganite ions. Recent intensive studies have shown that this DE framework must be subjected to the strong correlation between orbital degenerate electrons. On one hand, the orbital degeneracy itself leads to an anisotropic DE hopping being different from the conventional DE, which in turn may result in the anisotropy of the magnetic structure, such as the A-type or the C-type antiferromagnetism. On the other hand, the electronic correlation between these degenerate electrons plays an important role in determining the phases of the system. The correlation can come from both the on-site Coulomb interaction and the Jahn–Teller coupling between the lattice distortion and the electrons. The interplay of the DE mechanism and the strong electronic correlation leads to various magnetic, orbital and/or charge ordering as well as the phase separation.

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