Spontaneous voltage and persistent electric current from rectification of electronic noise in cuprate/manganite...

Non-reciprocal transport in solids under time-reversal symmetry is of great current interest. Here we show that YBa₂Cu₃O₇(YBCO)/Nd_0.65(Ca_0.7Sr_0.3)_0.35MnO₃(NCSMO) multilayers are promising candidates. By rectifying environmental electromagnetic fluctuations, they generate a spontaneous voltage of tens of millivolts, that can drive a persistent current across external circuits. The underlying ratchet-type potential presumably originates from the complex domain state of the NCSMO layers which host several nearly degenerate magnetic, electronic and polar orders. Particularly important appears to be the competition between a charge/orbital ordered majority phase with polar moments and a nonpolar ferromagnetic minority phase. A central role is also played by the adjacent YBCO layers that are too thin (≤10 nm) to fully screen the electric fields emanating from the NCSMO layers. These multilayers are useful for energy harvesting over broad temperature and magnetic field ranges, and for tunable multifunctional memory devices that are responsive to magnetic fields, electric currents, and electromagnetic radiation.