1. Doped rare-earth manganese oxides (manganites) exhibit a wide variety of physical phenomena due to complex interplay of electronic, magnetic, orbital, and structural degrees of freedom and their sensitivity to external fields. A photoinduced insulator to conductor transition in charge-ordered (CO) manganites is especially interesting from the point of view of creating photonic devices. We have found a considerable increase (up to 50%) of the photoinduced resistivity changes (Fig. 1a) in the Bi 0.4 Ca 0.6 MnO 3 thin film after covering the surface of the film with gold nanoparticles (colloidal gold) (Fig. 1b). This increase can be explained by enhancement of local electromagnetic (EM) field in the vicinity of the gold nanoparticle due to the plasmon resonance. Moreover, the lifetime of the photoinduced changes increases significantly after deposition of the gold nanoparticles on the surface of the film (Fig. 2a). From our previous studies we have found that the magnitude and the lifetime of photoinduced resistivity changes increases, when intensity illumination increases, which is probably due to the increase of the volume of conducting phase, created by light. Therefore, enhanced EM field in the vicinity of gold particles promotes a formation of larger volume of conducting phase (Fig. 2b). Fig. 2. (a) Temperature dependence of the time constant for the process shown in Fig. 1a after sample illumination was switched off for sample with gold nanoparticles on the surface (red) and without (blue.) (b) Schematic illustration of the appearance of photoinduced conductive phase (green) (upper panel) and the increase of the volume of this phase around gold nanoparticles. Plasmon Enhancement of Photoinduced Resistivity Changes in Bi 1-x Ca x MnO 3 Thin Films Vera Smolyaninova DMR-0348939 (a)(b) (a) Fig. 1. (a) Time dependence of the resistivity of the Bi 0.4 Ca 0.6 MnO 3 thin film at T = 170 K after illumination was switched on and off for sample with gold nanoparticles on the surface (red curve) and without (blue curve.) (b) AFM image of gold nanoparticles on the surface of Bi 0.4 Ca 0.6 MnO 3 thin film (b)

2. Education and Outreach Towson University is an undergraduate institution with strong emphases on undergraduate research. Three Towson students, Robert Kennedy, Suguru Yokoyama, and Gene Vanmeter, and one College of Notre Dame (local college, which does not have a research program) student Kim Wall were involved in this research. Robert J. Kennedy has defended his Departmental Honors Thesis based on his research. After graduation Robert Kennedy had become a high school science teacher, but continued his research in summer as REU/RET (Research Experience for Undergraduate/Teachers at Towson) team participant with undergraduate student Mark Steger from Albright College PA under the mentorship of the PI. To promote science among female students, the PI have organized a half-day long field trip to Towson University for 18 high school physics students (all girls) of Mercy High School, Towson, MD. The students showed active interest during demonstrations, visited different research, labs, received information about careers in physics. Plasmon Enhancement of Photoinduced Resistivity Changes in Bi 1-x Ca x MnO 3 Thin Films Vera Smolyaninova DMR-0348939 High school physics students learning about physics and materials research during their field trip to Towson University. Undergraduate students K. Wall and M. Steger at the REU/RET poster presentation. Undergraduate students M. Steger and high school science teacher R. Kennedy working in the lab.