Tunneling Electroresistance Induced by Interfacial
Phase Transitions in Ultrathin Oxide Heterostructures
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Abstract
The ferroelectric (FE) control of
electronic transport is one of
the emerging technologies in oxide heterostructures. Many previous
studies in FE tunnel junctions (FTJs) exploited solely the differences
in the electrostatic potential across the FTJs that are induced by
changes in the FE polarization direction. Here, we show that in practice
the junction current ratios between the two polarization states can
be further enhanced by the electrostatic modification in the correlated
electron oxide electrodes, and that FTJs with nanometer thin layers
can effectively produce a considerably large electroresistance ratio
at room temperature. To understand these surprising results, we employed
an additional control parameter, which is related to the crossing
of electronic and magnetic phase boundaries of the correlated electron
oxide. The FE-induced phase modulation at the heterointerface ultimately
results in an enhanced electroresistance effect. Our study highlights
that the strong coupling between degrees of freedom across heterointerfaces
could yield versatile and novel applications in oxide electronics