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Charge order quenching, Griffiths phase, and magnetotransport in polycrystalline Pr 0.58 Ca 0.42− y Sr y MnO 3 thin films
Author(s) -
Agarwal Vasudha,
Singh M. P.,
Siwach P. K.,
Fournier P.,
Singh H. K.
Publication year - 2010
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201026106
Subject(s) - magnetoresistance , condensed matter physics , colossal magnetoresistance , electrical resistivity and conductivity , orthorhombic crystal system , materials science , ferromagnetism , charge ordering , paramagnetism , doping , crystallite , analytical chemistry (journal) , magnetic field , charge (physics) , crystallography , chemistry , crystal structure , physics , metallurgy , chromatography , quantum mechanics
We report the magneto‐electrical properties of polycrystalline Pr 0.58 Ca 0.42− y Sr y MnO 3 thin films as function of Sr doping ( y ). These films (thickness ∼300 nm) prepared by spray pyrolysis on LaAlO 3 (100) single crystalline substrates are single phase and have orthorhombic structure. The Sr free films show charge ordering (CO) transition at T CO ≈ 240 K and the magnetic ground state has metamagnetic nature akin to the cluster glass (CG). Sr doping quenches CO and induces paramagnetic–ferromagnetic (PM–FM) transition with a systematic destabilization of the CG state. The PM–FM transition occurs at T C ≈ 182, 218, and 250 K for y = 0.06, 0.12, and 0.22, respectively. The Sr doping induced CO quenching also gives rise to the Griffiths phase (GP) at a temperature T G > T C . The resistivity of the Sr free films shows insulating behavior typical to the CO state. An insulator–metal transition (IMT) is observed at T IM ≈ 198 K in the y = 0.06 film, which increases to 225 and 265 K at y = 0.12 and 0.22, respectively. At y = 0.12, the sharpest IMT that results in huge temperature coefficient of resistivity (TCR) ≈19%, suggests the occurrence of a bicritical state. The bicriticality is also supported by a huge low field magnetoresistance ≈40% at 3 kOe and colossal magnetoresistance ≈90% at moderate magnetic field of 10 kOe. The destabilization of the CO, the appearance of GP, and the bicritical state has been explained in terms of the phase fluctuations induced by Sr doping dependent quenched disorder.