Magnetoresistance of artificial La0.7Sr0.3MnO3 grain boundaries as a function of misorientation angle

The resistance of polycrystalline doped ${\mathrm{LaMnO}}_{\mathrm{3}}$ materials has been shown to be highly sensitive to low magnetic fields. To enable direct study of the properties of isolated grain boundaries we have grown epitaxial ${\mathrm{La}}_{\mathrm{0.7}}{\mathrm{Sr}}_{\mathrm{0.3}}{\mathrm{MnO}}_{\mathrm{3}}$ films on a series of bicrystal substrates with different misorientation angles and patterned the films into a Wheatstone bridge geometry. We show that the grain boundary resistance and its magnetic field dependence vary strongly with the misorientation angle. The temperature dependence of the grain boundary resistance is also presented. We have obtained resistance changes of over 3% in fields of 2 mT at 300 K.