  Spin-dependent conductance across a manganate-barrier-manganate junction has
recently been demonstrated. The junction is a La$_{0.67}$Sr$_{0.33}$MnO$_3$%
-SrTiO$_3$-La$_{0.67}$ Sr$_{0.33}$MnO$_3$ trilayer device supporting
current-perpendicular transport. Large magnetoresistance of up to a factor of
five change was observed in these junctions at 4.2K in a relatively low field
of the order of 100 Oe. Temperature and bias dependent studies revealed a
complex junction interface structure whose materials physics has yet to be
understood.
