Low-frequency noise in patterned La0.7Sr0.3MnO3 thin films

Abstract

The low frequency noise in patterned La0.7Sr0.3MnO3 thin film bridges with different geometries was measured at 300 K in ambient magnetic field. Films were deposited by pulsed laser ablation on (100) SrTiO3 substrates. The measured 1/f noise was well described by the semiempirical Hooge relation, which indicates that the low frequency noise could be originated by resistance fluctuations. The measured noise magnitude was compared with bibliographic data for epitaxial La1−xSrxMnO3 (LSMO) and La1−xCaxMnO3 thin films. The normalized Hooge parameter α/n for our films was in the range of 2–4×10−28 m3, which is the order of magnitude of the best results reported in literature for oxygen annealed films. Finally the noise equivalent temperature of a thermometer fabricated with such LSMO films was estimated to be 3.4×10−6 K/Hz at 300 K, 10 Hz, and I=100 μA. These results demonstrate that the intrinsic low frequency noise of LSMO is not a limitation and that LSMO thin films can advantageously be used as performant thermometers for the fabrication of room temperature microbolometers.