Transport and magnetic properties of epitaxial and polycrystalline magnetite thin films

The transport and magnetic properties of magnetite (Fe3O4) thin Films grown epitaxially on single crystal MgO(100) and SrTiO3(100) substrates, and wit h multiple grain orientations on polycrystalline SrTiO3 substrates, have be en investigated. The films an grown using pulsed laser deposition and their epitaxial quality determined using ion channeling measurements. Transport and magnetic studies of Fe3O4 films as a function of thickness and morpholo gy suggest that epitaxial strain and growth defects affect the width and te mperature of the Verwey transition. In addition, these factors also signifi cantly influence the magnetic coercivity of the films. The low-field magnet oresistance (MR) behaviors of epitaxial and polycrystalline films as a func tion of temperature have been compared and they were found to be quite simi lar, suggesting very small contribution to the MR from grain boundaries. (C ) 1998 American Institute of Physics. [S0021-8979(98)17911-2].