Addressing the Challenges of Using Ferromagnetic Electrodes in the Molecular Spintronics Devices

TL;DR

This study explores NiFe as a ferromagnetic electrode for molecular spintronics devices, demonstrating its resistance to oxidation and mechanical stress, thus enabling more reliable device fabrication.

Contribution

It introduces NiFe as a viable ferromagnetic electrode material, addressing oxidation and stress challenges in molecular spintronics device fabrication.

Findings

NiFe oxidizes beyond 90°C, limiting high-temperature processing.

Aged or mildly heated NiFe surfaces are suitable for chemical bonding.

NiFe exhibits excellent etching resistance and minimal deformation.

Abstract

Ferromagnetic electrodes chemically bonded with thiol functionalized molecules can produce novel molecular spintronics devices. However, major challenges lie in developing Ferromagnetic electrodes based commercially viable device fabrication scheme that consider the susceptibility of ferromagnetic electrodes to oxidation, chemical etching, and stress induced deformations during fabrication and usage. This paper studies NiFe, an alloy used in the present day memory devices and high-temperature engineering applications, as a candidate FM electrode for the fabrication of MSDs. Our spectroscopic reflectance studies show that NiFe start oxidizing aggressively beyond 90 C. The NiFe surfaces, aged for several months or heated for several minutes below 90 C, exhibited remarkable electrochemical activity and were suitable for chemical bonding with the thiol functionalized molecular device elements. NiFe also demonstrated excellent etching resistance and minimized the mechanical stress induced deformities. This paper demonstrates the successful utilization of NiFe electrodes in the tunnel junction based molecular device fabrication approach. This paper is expected to fill the knowledge gap impeding the experimental development of ferromagnetic electrode based molecular spintronics devices for realizing novel logic and memory devices and observing a numerous theoretically predicted phenomenon.