Abstract
The magnetic, structural, and transport properties of pulsed-laser deposited LaMnO3 thin films are analyzed as a function of the O2 partial pressure in the growth environment (using an O2/Ar gas mixture). Interestingly, the magnetic properties do not change gradually as the O2 content increases. Instead, ferromagnetism emerges rapidly with oxygen; a critical amount of Ar is needed to suppress ferromagnetism effectively in LaMnO3 thin films. The most dramatic suppression of ferromagnetism occurs only in the narrow window below 10% oxygen, where the ferromagnetic moments decrease by a factor of 20. Above a certain oxygen concentration, the ferromagnetic moment no longer increases with oxygen. The sample grown in pure oxygen shows a metal-insulator (MI) transition at ~ 200 K, but exhibits an insulating behavior again below ~150K. This intermediate metallic behavior is significantly suppressed by using the O2/Ar gas mixture.
