Room-temperature ferromagnetism in Sn1-xMnxO2 nanocrystalline thin films prepared by ultrasonic spray pyrolysis

摘要

Sn1-xMnxO2 (x = 0.01-0.05) thin films were synthesized on quartz substrate using an inexpensive ultrasonic spray pyrolysis technique. The influence of doping concentration and substrate temperature on structural and magnetic properties of Sn1-xMnxO2 thin films was systematically investigated. X-ray diffraction (XRD) studies of these films reflect that the Mn3+ ions have substituted Sn4+ ions without changing the tetragonal rutile structure of pure SnO2. A linear increase in c-axis lattice constant has been observed with corresponding increase in Mn concentration. No impurity phase was detected in XRD patterns even after doping 5 at% of Mn. A systematic change in magnetic behavior from ferromagnetic to paramagnetic was observed with increase in substrate temperature from 500 to 700 degrees C for Sn1-xMnxO2 (X = 0.01) films, Magnetic studies reveal room-temperature ferromagnetism (RTFM) with 3.61 x 10(-4) emu saturation magnetization and 92 Oe coercivity in case of Sn1-xMnxO2 (x = 0.01) films deposited at 500 degrees C. However, paramagnetic behavior was observed for the films deposited at a higher substrate temperature of 700 degrees C. The presence of room-temperature ferromagnetism in these films was observed to have an intrinsic origin and could be obtained by controlling the substrate temperature and Mn doping concentration.