Photoinduced resistivity changes in Bi0.4Ca0.6MnO3 thin films

Abstract

We report charge-ordered Bi0.4Ca0.6MnO3 thin films with charge-ordering temperature near room temperature, and observation of large photoinduced resistivity changes in these films associated with melting of the charge ordering by visible light. Films grown under small compressive strain exhibit the largest photoinduced resistivity changes. The lifetime of the photoinduced low-resistance state is on the order of half a minute. These photoinduced resistivity changes in thin films of Bi0.4Ca0.6MnO3 make them very promising for photonic device application.

The effect of strain and strain symmetry on the charge-order transition in Bi0.4Ca0.6MnO3films

“…Figure 2(a) and (b) shows the resistivity versus temperature ((T)) curves of BCMO films on different substrates. Turning our attention first to the (001)-oriented substrates, we observe that the film grown on the (001) LAO substrate exhibits a well-defined phase transition near 270 K, significantly lower than the bulk value of 330 K [30] but consistent with earlier published work on epitaxial films [45]. In contrast, the sample grown on (001) STO shows only a very diffuse transition.…”

Colossal resistivity change associated with the charge ordered/disordered transition: Monte Carlo study

“…Although the CO states are stable against magnetic field or pressure below the threshold, they are sensitive to the site disorder, because of the cooperative lattice effect [8]. Local illumination [14][15][16][17] may have the same effect as local site disorder. It was demonstrated [14,15] that illumination may even cause the IMT process rather than the XR sequence, because the DE sequence cannot be avoided in these manganites.…”

“…These behaviors will not be observable for La 2/3 Sr 1/3 MnO 3 in which the resistivity response to the magnetic field is nearly linear [13], since no CO state exists in La 2/3 Sr 1/3 MnO 3 . Second, for manganites of intermediate and narrow bandwidth, e.g., Pr 1-x Ca x MnO 3 , the IMT or colossal reduction of resistivity can be induced by external fluctuations other than magnetic field, such as photon illumination [14][15][16][17], electric current [18,19], and pressure [20,21]. These phenomena cannot be predicted in the magnetic framework.…”

Nonbolometric photoresponse in (La,Pr)0.67Ca0.33MnO3 thin films

“…10 In the present context of mixed phase manganite systems, this issue is particularly relevant, given the fact the charge ordered state is known to be susceptible to radiation over a wide range of wavelengths. [11][12][13] Nonthermal effects, when present, are also valuable in terms of understanding the physics of the metal-insulator transitions. We have therefore studied the radiation-induced resistance changes in the mixed phase manganite system ͑LaPr͒ 0.67 Ca 0.33 MnO 3 ͑LPCMO͒.…”

“…As mentioned earlier, Pr doping is known to introduce the coexistence of charge ordered insulating and ferromagnetic metallic regions within the material. It is known that charge ordering in several manganite systems, including ͑Pr 1−x Ca x MnO 3 ͒, can be destroyed by radiation over a broad wavelength range, [11][12][13] thus promoting metallicity. However, if the observed nonthermal effect was caused by the light-induced destruction of charge ordering, one would expect the light-induced resistance decrease to persist at lower temperatures, contrary to our observation that it is confined to the percolative transition region.…”