Broadband voltage rectifier induced by linear bias dependence in CoFeB/MgO magnetic tunnel junctions

TL;DR

This paper demonstrates how tailoring perpendicular magnetic anisotropy in CoFeB/MgO magnetic tunnel junctions enables a broadband voltage rectifier with high RF to DC conversion efficiency, useful for wireless energy harvesting.

Contribution

It introduces a method to produce a linear resistance dependence in MTJ nano-pillars for efficient broadband rectification based on bias dependence.

Findings

Achieved RF to DC conversion efficiency up to 11%.

Demonstrated zero-threshold broadband voltage rectification.

Controlled PMA to tune resistance dependence.

Abstract

In this paper, the perpendicular magnetic anisotropy (PMA) is tailored by changing the thickness of the free layer with the objective of producing MTJ nano-pillars with smooth linear resistance dependence with both in-plane magnetic field and DC bias. We furthermore demonstrate how this linear bias dependence can be used to create a zero-threshold broadband voltage rectifier, a feature which is important for rectification in wireless charging and energy harvesting applications. By carefully balancing the amount of PMA acting in the free layer the measured RF to DC voltage conversion efficiency can be made as large as 11%.