Diamagnetic to ferromagnetic switching in VO2 epitaxial thin films by nanosecond excimer laser treatment

VO2(010)/NiO(111) epitaxial heterostructures were integrated with Si(100) substrates using a cubic yttria-stabilized zirconia (c-YSZ) buffer. The epitaxial alignment across the interfaces was determined to be VO2(010)parallel to NiO(111)parallel to c-YSZ(001)parallel to Si(001) and VO2[100]parallel to NiO < 110 >parallel to c-YSZ < 100 >parallel to Si < 100 >. The samples were subsequently treated by a single shot of a nanosecond KrF excimer laser. Pristine as-deposited film showed diamagnetic behavior, while laser annealed sample exhibited ferromagnetic behavior. The population of majority charge carriers (e(-)) and electrical conductivity increased by about two orders of magnitude following laser annealing. These observations are attributed to the introduction of oxygen vacancies into the VO2 thin films and the formation of V3+ defects. (C) 2013 AIP Publishing LLC.