A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Effect of strain and grain boundaries on dielectric properties in La0.7Sr0.3MnO3 thin films
Tekijät: Majumdar S, Huhtinen H, Paturi P, Majumdar HS
Kustantaja: SPRINGER
Julkaisuvuosi: 2013
Journal: Journal of Materials Science
Tietokannassa oleva lehden nimi: JOURNAL OF MATERIALS SCIENCE
Lehden akronyymi: J MATER SCI
Numero sarjassa: 5
Vuosikerta: 48
Numero: 5
Aloitussivu: 2115
Lopetussivu: 2122
Sivujen määrä: 8
ISSN: 0022-2461
DOI: https://doi.org/10.1007/s10853-012-6986-x
Tiivistelmä
High dielectric constant and its dependence on structural strain and grain boundaries (GB) in La0.7Sr0.3MnO3 (LSMO) thin films are reported. X-ray diffraction, magnetization, and magneto-transport measurements of the LSMO films, made by pulsed laser deposition on two different substrates-MgO and SrTiO3 (STO), were compared to co-relate magnetic properties with dielectric properties. At room temperature, in the ferromagnetic phase of LSMO, a high dielectric constant (6 x 10(4)) was observed up to 100 kHz frequency for the films on MgO, with polycrystalline properties and more high-angle GB related defects, while for the films on STO, with single-crystalline properties but strained unit cells, high dielectric constant (a parts per thousand 10(4)) was observed until 1 MHz frequency. Also, a large dielectric relaxation time with significant broadening from the Debye single-dielectric relaxation model has been observed in samples with higher GB defects. Impedance spectroscopy further shows that large dielectric constant of the single-crystalline, strained LSMO film is intrinsic in nature while that in the polycrystalline films are mainly extrinsic due to higher amount of GBs. The presence of high dielectric constant value until high frequency range rules out the possibility of "apparent giant dielectric constant" arising from the sample-electrode interface. Coexistence of ferromagnetism and high dielectric constant can be very useful for different microelectronic applications.
High dielectric constant and its dependence on structural strain and grain boundaries (GB) in La0.7Sr0.3MnO3 (LSMO) thin films are reported. X-ray diffraction, magnetization, and magneto-transport measurements of the LSMO films, made by pulsed laser deposition on two different substrates-MgO and SrTiO3 (STO), were compared to co-relate magnetic properties with dielectric properties. At room temperature, in the ferromagnetic phase of LSMO, a high dielectric constant (6 x 10(4)) was observed up to 100 kHz frequency for the films on MgO, with polycrystalline properties and more high-angle GB related defects, while for the films on STO, with single-crystalline properties but strained unit cells, high dielectric constant (a parts per thousand 10(4)) was observed until 1 MHz frequency. Also, a large dielectric relaxation time with significant broadening from the Debye single-dielectric relaxation model has been observed in samples with higher GB defects. Impedance spectroscopy further shows that large dielectric constant of the single-crystalline, strained LSMO film is intrinsic in nature while that in the polycrystalline films are mainly extrinsic due to higher amount of GBs. The presence of high dielectric constant value until high frequency range rules out the possibility of "apparent giant dielectric constant" arising from the sample-electrode interface. Coexistence of ferromagnetism and high dielectric constant can be very useful for different microelectronic applications.
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