Radiofrequency harvesting using ambient wireless energy could be used to reduce the carbon footprint of electronic devices. However, ambient radiofrequency energy is weak (less than -20 dBm), and thermodynamic limits and high-frequency parasitic impedance restrict the performance of state-of-the-art radiofrequency rectifiers. Nanoscale spin rectifiers based on magnetic tunnel junctions have recently demonstrated high sensitivity, but suffer from a low a.c.-to-d.c. conversion efficiency (less than 1%). Here, we report a sensitive spin rectifier rectenna that can harvest ambient radiofrequency signals between -62 and -20 dBm. We also develop an on-chip co-planar waveguide-based spin rectifier array with a large zero-bias sensitivity (around 34,500 mV/mW) and high efficiency (7.81%). Self-parametric excitation driven by voltage-controlled magnetic anisotropy is a key mechanism that contributes to the performance of the spin-rectifier array. We show that these spin rectifiers can wirelessly power a sensor at a radiofrequency power of -27 dBm.
@article{arxiv.2408.01160,
title = {Nanoscale spin rectifiers for harvesting ambient radiofrequency energy},
author = {Raghav Sharma and Tung Ngo and Eleonora Raimondo and Anna Giordano and Junta Igarashi and Butsurin Jinnai and Shishun Zhao and Jiayu Lei and Yong-Xin Guo and Giovanni Finocchio and Shunsuke Fukami and Hideo Ohno and Hyunsoo Yang},
journal= {arXiv preprint arXiv:2408.01160},
year = {2024}
}