Visible-light induced persistent photoconductivity in trilayered films of perovskite manganites

The persistent photoconductivity (PPC) effect has been observed in trilayered films made of perovskite manganites La2/3Ca1/3MnO3/(La0.3Nd0.7)(2.3)Ca1/3MnO3La2/3Ca1/3MnO3(LNL) induced by He-Ne laser with wavelength of 632.8 nm. According to the result obtained in the thin film of (La0.3Nd0.7)(2/3)Ca1/3MnO3(LNCMO), which the PPC effect is also observed below similar to 50 K, the PPC effect observed in trilayered film LNL should originate from the middle layer LNCMO. Compared with the thin film of LNCMO, the PPC effect of the trilayered film LNL appears at similar to 86 K, which is higher than that of LNCMO at similar to 50 K. The PPC effect of LNL can be quenched on thermal cycling in the vicinity of 98 K, which is also higher than that of LNCMO at similar to 77 K. The difference of PPC behavior between the thin films of LNCMO and LNL can be attributed to the variation of cluster-glass state in the trilayered films of LNL caused by the strong coupling of interlayer between the middle layer LNCMO and the top/bottom layers LCMO. (C) 2001 American Institute of Physics.