Magnetic coercive field changes in microstructured (La$_{\mathrm{1-y}}$Pr$_{\mathrm{y}})_{\mathrm{1-x}}$Ca$_{\mathrm{x}}$MnO$_{3}$ thin films

The hole-doped manganite (La$_{\mathrm{1-y}}$Pr$_{\mathrm{y}})_{\mathrm{1-x}}$Ca$_{\mathrm{x}}$MnO$_{3}$ (LPCMO) shows effects such as phase coexistence and colossal magnetoresistance. Since the phase coexistence occurs at length scales of up to 10 micrometers, it is relatively straightforward to reduce the sample size to the scale of phase separation. We will present magnetization data that show a change in the magnetic coercive fields of LPCMO thin films by a factor of about 2 when the sample size is reduced to 100 micrometers using a photolithography process. The amount of the increase of the coercive field increases with film thickness. We will discuss the increased coercive field in the context of the competition between shape and stress magnetic anisotropies. We will also describe the role of dimensionality in determining the coercive field behavior. This process can be used to control the phase separation and the magnetic hardness of manganites.