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

## TL;DR

Researchers discovered that certain layered materials can generate a spontaneous voltage and persistent current from environmental electromagnetic noise, useful for energy harvesting and memory devices.

## Contribution

The study introduces a novel mechanism for non-reciprocal transport in cuprate/manganite heterostructures via rectification of electronic noise.

## Key findings

- YBCO/NCSMO multilayers generate spontaneous voltages of tens of millivolts from electromagnetic fluctuations.
- The voltage arises from a ratchet-type potential due to competing magnetic and electronic orders in NCSMO layers.
- These structures are effective for energy harvesting and tunable memory devices across various temperatures and magnetic fields.

## Abstract

Non-reciprocal transport in solids under time-reversal symmetry is of great current interest. Here we show that YBa2Cu3O7(YBCO)/Nd0.65(Ca0.7Sr0.3)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.

Nonreciprocal transport is sensitive to the broken inversion symmetry of the electronic state. Here, the authors demonstrate a spontaneous voltage signal which they suggest is time-reversal-even and arises from a ratchet-type electronic potential.