Phase separation effects in charge-ordered Pr 0.5 Ca 0.5 MnO 3 thin film (original) (raw)
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Charge-order melting and magnetic phase separation in thin films of Pr0.7Ca0.3MnO3
Physical Review B, 2009
We investigate the effect of strain on the phenomenon of charge-order melting, that is the transformation of a charge-ordered insulating state to a metallic state under the influence of a magnetic field ͑the melting field͒ in thin films of Pr 0.7 Ca 0.3 MnO 3 grown on various substrates. We find that unstrained films grown on SrLaGaO 4 behave quite similar to bulk material, but that strained films grown on SrTiO 3 and NdGaO 3 show hugely increased melting fields. Strain relaxation by postannealing again leads to bulklike behavior. In this material the antiferromagnetic charge-order phase can coexist with a ferromagnetic insulating state. Magnetization measurements, where we demonstrate the presence of exchange bias effects, show that this is also the case in the strained films. We argue that the phase mixture in the strained films is more difficult to melt than in the unstrained case.
Applied Physics Letters, 2010
We report the magnetoelectrical properties of polycrystalline Pr 0.58 Ca 0.42 MnO 3 thin films ͑thicknessϳ 300 nm͒ deposited on single crystal LaAlO 3 ͑LAO͒ and SrTiO 3 ͑STO͒ substrates. The films on LAO show charge ordering ͑CO͒ at T CO Ϸ 240 K, with a metamagnetic ground state akin to the cluster glass ͑CG͒. In PCMO/STO films the CO is quenched and enhanced magnetic moment in the CG state suggests stronger ferromagnetic component. The resistivity of the films on LAO and STO differ drastically, the former has temperature dependence typical to the CO state, while the later show thermal cycling dependent insulator-metal transition ͑IMT͒. The large hysteresis in the temperature dependent resistivity provides the evidence of cluster coexistence. The films on STO also exhibit colossal magnetoresistance ͑CMRϳ 91%͒ at moderate magnetic field ͑ϳ10 kOe͒. The CO quenching, IMT, and CMR are explained in terms of the substrate induced magnetoelectrical phase coexistence.
Applied Physics Letters, 2010
We report the magnetoelectrical properties of polycrystalline Pr 0.58 Ca 0.42 MnO 3 thin films ͑thicknessϳ 300 nm͒ deposited on single crystal LaAlO 3 ͑LAO͒ and SrTiO 3 ͑STO͒ substrates. The films on LAO show charge ordering ͑CO͒ at T CO Ϸ 240 K, with a metamagnetic ground state akin to the cluster glass ͑CG͒. In PCMO/STO films the CO is quenched and enhanced magnetic moment in the CG state suggests stronger ferromagnetic component. The resistivity of the films on LAO and STO differ drastically, the former has temperature dependence typical to the CO state, while the later show thermal cycling dependent insulator-metal transition ͑IMT͒. The large hysteresis in the temperature dependent resistivity provides the evidence of cluster coexistence. The films on STO also exhibit colossal magnetoresistance ͑CMRϳ 91%͒ at moderate magnetic field ͑ϳ10 kOe͒. The CO quenching, IMT, and CMR are explained in terms of the substrate induced magnetoelectrical phase coexistence.
Magnetic properties of the insulating ferromagnetic phase in strained Pr0.6Ca0.4MnO3 thin films
Applied Physics Letters, 2008
Bulk magnetization in Pr 0.6 Ca 0.4 MnO 3 thin films with tensile (SrTiO 3) and compressive (LaAlO 3) substrate-induced strain is compared to the magnetooptical Kerr effect (MOKE) measurements. In the absence of an external magnetic field, in both films, a stable ferromagnetic insulating majority phase coexists with an antiferromagnetic insulating phase below ∼120K. MOKE measurements indicate that at 5K a metastable ferromagnetic metallic (FM) phase is formed at the surface of the stretched film in a magnetic field below 1.1T already, while in the bulk the FM phase starts to form in the field above ∼ 4T in both films.
Journal of Physics: Condensed Matter, 2016
With the goal of elucidating the background of photoinduced ferromagnetism phenomena observed in the perovskite structured (Pr,Ca) manganites, the low-temperature magnetostructure of the material Pr Ca MnO 0.9 0.1 3 was revised using cold neutron powder diffraction, SQUID magnetometry and ab initio calculations. Particular emphasis was placed on determining the presence of nanoscale magnetic phase separation. Previously published results of a canted A-AFM average ground state were reproduced to a good precision both experimentally and theoretically, and complemented by investigating the effects of an applied magnetic field of 2.7 T on the magnetostructure. Explicit evidence of nanoscale magnetic clusters in the material was obtained based on high-resolution neutron diffractograms. Along with several supporting arguments, we present this finding as a justification for extending the nanoscale magnetic phase separation model of manganites to the material under discussion despite its very low Ca doping level in the context of the model. In the light of the new data, we also conclude that the low temperature magnetic moment of Pr must be ca. 300% larger than previously thought in this material, close to the high spin value of µ 2 B per formula unit.
Ferromagnetic and charge ordering competition in strained thin films of La1−xCaxMnO3 system
Vacuum, 2004
Thin films of La 1Àx Ca x MnO 3 (x ¼ 0:3; 0.51) have been deposited on LaAlO 3 (LAO) and SrTiO 3 (STO) substrates by magnetron sputtering (MS) and pulsed laser deposition (PLD). Lattice strain induced by substrate misfit results in drastic change of transport and magnetic properties. The very thin sample (thickness of $15 nm) with x ¼ 0:3 deposited by MS on LAO substrate reveals compressive strained layer and semiconducting behaviour in zero magnetic field. Application of strong magnetic field of 7.5 T leads to metallic behaviour and metal-insulator transition at a temperature about a bulk value of 250 K. A sharp transition to a low-resistive state above a certain magnetic field is found at To50 K and associated with a significant hysteresis. Such a behaviour is similar to the phenomenon of melting of a charge ordered state by magnetic field that is first-order transition. Samples with substitution rate of x ¼ 0:51 deposited by PLD on LAO and STO substrates showed different behaviour due to variable strain of manganite layer. Magnetotransport properties of strained thin films are discussed due to the coexistence of ferromagnetic metallic and charge-ordered insulating phases and percolation processes. r
Journal of Applied Physics, 2003
Epitaxial thin films of ferromagnet/insulator/ferromagnet layers (La0.7Ca0.3MnO3/LaAlO3/La0.7Sr0.3MnO3) of different thickness were fabricated by pulsed laser deposition. Microstructural analysis shows island growth on the thicker film surface. dc magnetization study demonstrates the strong signature of domain wall freezing for the composite film. An interesting feature is a cusp/upturn in field-cooled curve in the composite film-1, much below TB, the blocking temperature. The low temperature cusp disappears in the composite film-2. We suggest that a quasistable charge ordering via spin localization at low temperature, especially for film-1, is the origin of this feature.