Journal ArticleDOI
Irreversible electronic and magnetic transformations in colossal magnetoresistance compositions close to charge ordering
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TLDR
In this article, the resistivity and ac susceptibility of two colossal magnetoresistace compositions have been measured in air and shown to be very close to charge ordering, and the time changes in the magnetization are logarithmic in general.Abstract:
We report the measurements of resistivity and ac susceptibility in two colossal magnetoresistanace compositions $({\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3},x=0.50,0.52)$ close to charge ordering, which have been prepared in air. With time and thermal cycling $(Tl300 \mathrm{K})$ there is an irreversible transformation of the low-temperature phase from a partially ferromagnetic and metallic to one that is less ferromagnetic and highly resistive. The time changes in the magnetization are logarithmic in general and activation energies are consistent with those expected for electron transfer between Mn ions. The data suggest that oxygen nonstochiometry results in mechanical strains in this two-phase system, leading to the development of metastable states which relax towards the more stable charge-ordered and antiferromagnetic microdomains.read more
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Ac study of 10% Fe-doped La0.65Ca0.35MnO3 material by impedance spectroscopy
TL;DR: In this paper, complex impedance analysis over the frequency and temperature ranges of 1-100 kHz and 77-323 K, respectively around the metal-insulator transition temperature capacitative effect has been observed which may be due to clustering of defects induced by iron doping.
Journal ArticleDOI
Increase of grain boundary resistance with time by impedance spectroscopy in La0.50Ca0.50MnO3+δ at 77 K
TL;DR: In this paper, the effects of grain boundaries on the electrical properties of La 0.50 Ca 0.5 MnO 3+δ impedance spectroscopic studies have been carried out at 77 K.
Journal ArticleDOI
Melting/collapse of charge orbital ordering and spread of relaxation time with frequency in La0.50Ca0.50MnO3+δ by impedance spectroscopy
M. Nadeem,M. J. Akhtar +1 more
TL;DR: In this paper, the microscopic nature of the charge/orbital ordering (COO) in polycrystalline La0.50Ca0.3+δ sample at different temperatures was investigated.
Journal ArticleDOI
Change of conduction mechanism in the impedance of grain boundaries in Pr0.4Ca0.6MnO3
Matiullah Shah,Matiullah Shah,Muhammad Nadeem,Muhammad Idrees,Muhammad Idrees,Muhammad Atif,Muhammad Javed Akhtar +6 more
TL;DR: In this article, a polycrystalline Pr 0.4 Ca 0.6 MnO 3 sample has been analyzed by employing X-ray diffraction, magnetization and impedance spectroscopic techniques.
Change of conduction mechanism in the impedance of grain boundaries
TL;DR: In this paper, a polycrystalline Pr0.4Ca0.6MnO3 sample has been analyzed by employing X-ray diffraction, magnetization and impedance spectroscopic techniques.
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Physics of magnetism
TL;DR: Paleomagnetism is the study of the magnetic properties of rocks as discussed by the authors, and it is one of the most broadly applicable disciplines in geophysics, having uses in diverse fields such as geomagnetic, tectonics, paleoceanography, volcanology, paleontology, and sedimentology.