Raman scattering studies of field- and temperature-dependent melting of charge order in La$_{1-x}$Ca$_{x}$MnO$_{3}$

The La$_{1-x}$Ca$_{x}$MnO$_{3}$ is one of the well-known perovskite manganites that display charge ordering behavior below a charge ordering temperature T$_{co}$ for x $\ge $ 0.5. In particular, the strongest ordering is shown at commensurate doping x=0.5 with the transition temperature, T$_{CO}$=160K. We investigate the field-induced melting of charge ordering in this system using field-dependent Raman scattering at different temperatures. By monitoring the field- and doping-dependence of excitations specific to the charge-ordered state, we are able to sensitively monitor the breakdown of both long-range and local charge order, and to carefully examine the stability of the charge ordered state to both doping (x) and applied magnetic field.