Comparison of Sol-Gel Derived and Pulsed Laser Deposited Epitaxial Lao Films for IR Bolometer

摘要

Epitaxial La_(0.67)Ca_(0.33)MnO_3 films have been prepared on LaAlO_3 crystals by pulsed laser deposition (PLD) and by a novel all-alkoxide sol-gel technique. Different out-of-plane lattice parameters are found for the as-prepared films, and scanning electron microscopy shows a more porous structure for sol-gel films as compared to PLD films. These differences are largely removed by post-annealing at 1000 ℃. Transport measurements show maximum temperature coefficient of resistivity of 8.2 % K~(-1) at 258 K (PLD) and 6.1 % K~(-1) at 241 K (sol-gel) and colossal magnetoresistance at 7 kOe of 35 % at 263 K (PLD) and 32 % at 246 K (sol-gel).