Enhancement of Photoinduced Effects in Annealed Bi1-xCaxMnO3 thin films

Doped rare-earth manganese oxides (manganites) exhibit a wide variety of fascinating properties and phenomena. A photoinduced insulator-to-conductor transition in charge-ordered manganites is especially interesting from the point of view of creating photonic devices. We studied the effects of annealing of manganite materials in order to better understand nature of photoinduced effects in manganites.  We found that

  • Photoinduced changes in annealed film are significantly larger than in as-prepared film.
  • The life time of the photoinduced changes are much larger in annealed films (up to 30 times at low temperatures).
  • Probable origin of photoinduced effect enhancement is trapping of electrons by oxygen vacancies, which introduces more charge carriers and weakens the charge ordering.
  • Increased magnitude of the photoinduced changes (and hence the optical contrast between insulating and photoinduced conducting phases) and their increased life time are desirable for potential photonic device applications.
BCMO1[1]
Temperature dependence of resistivity of BCMO annealed and as-prepared thin films with (dotted lines) and without laser light illumination (solid lines). The inset shows the current-voltage contact configuration
BCMO2[1]
The lifetime of the photoinduced conducting phase as function of temperature

 

 

 

 

 

 

 

 

This work is supported by NSF Grant DMR-0348939.  These results are published in Journal of Applied Physics (V. N. Smolyaninova et al., JAP 106, 043902 (2009)).