Ferroelectric control of a Mott insulator

The electric field control of functional properties is an important goal in oxide-based electronics. To endow devices with memory, ferroelectric gating is interesting, but usually weak compared to volatile electrolyte gating. Here, we report a very large ferroelectric field-effect in perovskite heterostructures combining the Mott insulator CaMnO(3) and the ferroelectric BiFeO(3) in its “supertetragonal” phase. Upon polarization reversal of the BiFeO(3) gate, the CaMnO(3) channel resistance shows a fourfold variation around room temperature, and a tenfold change at ~200 K. This is accompanied by a carrier density modulation exceeding one order of magnitude. We have analyzed the results for various CaMnO(3) thicknesses and explain them by the electrostatic doping of the CaMnO(3) layer and the presence of a fixed dipole at the CaMnO(3)/BiFeO(3) interface. Our results suggest the relevance of ferroelectric gates to control orbital- or spin-ordered phases, ubiquitous in Mott systems, and pave the way toward efficient Mott-tronics devices.