1/f electrical noise in epitaxial thin films of the manganite oxides La0.67Ca0.33MnO3 and Pr0.67Sr0.33MnO3

Abstract

We report measurements of 1/f electrical noise in two hole doped manganite perovskite oxides, La 0.67 Ca 0.33 MnO 3 and Pr 0.67 Sr 0.33 MnO 3 , which exhibit colossal magnetoresistance. The noise magnitude represented by the Hooge parameter is nearly 8 orders of magnitude larger than that observed in ordinary metals ͑and semiconductors͒ and nearly 5-6 orders of magnitude larger than that observed in epitaxial films of the perovskite oxide YBa 2 Cu 3 O 7 in the normal state. The normalized noise spectral density increases with decreasing temperature below the resistivity peak, suggestive of the presence of additional low energy noise processes in the ferromagnetic metallic state.

The epitaxial growth of the LaCaMnO thin films with the CMR effects prepared by a new method: Precursor film sintering

“…Lanthanum manganese oxide La 1Àx A x MnO 3 (''A'' representing doped divalent cations such as Ca, Sr, Ba) films with a perovskite-type crystal structure have drawn remarkable interests for their very large magneto-resistance (MR) effects known as giant MR or colossal magneto-resistance (CMR) [1,2]. For example, Chahara et al [3] prepared La 0.72 Ca 0.25 MnO z films by an ion beam sputtering method, from which the MR (defined as DR/R 0 ) of 53% was achieved in a magnetic field of 1 Â 10 4 Oe at 220 K. Jin et al [4] reported that the epitaxial LaCaMnO films deposited on LaAlO 3 (1 0 0) substrates prepared by the pulsed laser deposition (PLD) had a large MR as high as 99.9% at 77 K and 92.8% at room temperature at a magnetic field of 6 T, respectively.…”

Low-frequency1/fnoise in doped manganite grain-boundary junctions

“…[21][22][23][24][25] In particular, a large noise peak close to the Curie temperature T C has been interpreted in terms of a percolative nature of the transition between charge-ordered insulating and ferromagnetic metallic states. 26,27 Reutler et al 28 showed that the unusually large noise level is not an intrinsic property of the doped manganites.…”

Room-temperature relaxation of the electrical resistance and electrical 1/fα noise observed at very low frequency in the remanent state of glass-ceramics containing magnetite nanoparticles

“…1 for sample A (this curve is representative of all studied samples). A non-saturating, monotonic growth of R with time is found up to 7.8 Â 10 4 s, indicating the development of a magnetic disorder that decreases the hopping conductance between adjacent magnetite particles [6]. The initial electrical resistivity for such a material is calculated to be 2.8 Om, to be compared with the value of 0.5 Om found in compacted magnetite powders [8].…”

“…Transport measurements on magnetic oxides reveal a notable amount of resistance fluctuations leading to a 1/f-type noise [6]. Recently, low-frequency electrical noise has been observed in films of Fe 3 O 4 (a half-metallic oxide) obtained by molecular-beam epitaxy, and explained in terms of conductance fluctuations occurring in the conductive hopping regime [7].…”