Memristive Switching and Interfacial Magnetoelectricity in LCMO/PBCO Heterostructure

New phenomena emerge at the interfaces of transition metal oxides. Here we report memristive switching in a La$_{0.7}$Ca$_{0.3}$MnO$_{3}$PrBa$_{2}$Cu$_{3}$O$_7$ bilayer structure with an On/Off ratio greater than 10$^3$ that originates from a new type of interfacial magnetoelectricity. Using DFT calculations, we show that at the LCMO/PBCO interface, a ``magnetic dead layer (MDL)''\footnote{W. Luo, S. J. Pennycook, S. T. Pantelides, Phy. Rev. Lett. 101, 247204 (2008)} can be switched on and off by a small displacement of the interfacial Mn atoms generated by an external voltage. Initially, the LCMO is ferromagnetic with no MDL. This is the Low Resistance State (LRS) as majority-spin carriers tunnel through the PBCO. A negative voltage creates an electric field that displaces the interfacial Mn atoms towards the bulk LCMO by a few hundredths of an Angstrom. In such position, the interfacial Mn layer is coupled anti-ferromagnetically to the bulk LCMO, whereby a MDL is present, adding a barrier for the majority-spin carriers to tunnel and thus the bilayer is at High Resistance State (HRS). A positive bias drives the Mn atoms back to their original positions that favor ferromagnetic coupling, thus destroying the MDL and switching the bilayer back to LRS.