Colossal magnetocapacitance in manganites

Thin films of strongly correlated electron materials grown epitaxially on planar substrates typically have anisotropic properties that are usually not captured by edge-mounted four-terminal electrical measurements. In collaboration with Prof. A. F. Hebard’s group we have studied the anisotropic transport in phase-separated manganite thin films by using an unconventional arrangement of contact electrodes (Figure (a)) that enables the simultaneous determination of colossal magnetoresistance associated with d.c. transport parallel to the film substrate and colossal magnetocapacitance associated with a.c. transport in the perpendicular direction.We distinguish two distinct direction-dependent Insulator to Metal transitions (ref. Nature Physics (2007), (Published online: doi:10.1038/nphys626)) .

	(a) Cross-sectional view of the trilayer capacitor structure comprising the LPCMO base electrode, the AlOx dielectric and the Al counter electrode. (b) temperature-dependent resistance (parallel transport) capacitance (perpendicular transport).