Antiferromagnetic MnNi tips for spin-polarized scanning probe microscopy

TL;DR

This paper introduces a new method for fabricating spin-polarized scanning tunneling microscopy tips using antiferromagnetic MnNi foil, offering improved performance and zero-field operation for magnetic studies.

Contribution

It presents a straightforward fabrication process for antiferromagnetic MnNi tips that are intrinsically spin-polarized, enhancing SP-STM capabilities.

Findings

Tips demonstrate spin sensitivity through Ho atom magnet switching measurements.

Tips show comparable STM performance to conventional tips.

Fabrication process is simple and uses commercially available materials.

Abstract

Spin-polarized scanning tunneling microscopy (SP-STM) measures tunnel magnetoresistance (TMR) with atomic resolution. While various methods for achieving SP probes have been developed, each is limited with respect to fabrication, performance, and allowed operating conditions. In this study, we present the fabrication and use of SP-STM tips made from commercially available antiferromagnetic $\rm{Mn_{88}Ni_{12}}$ foil. The tips are intrinsically SP, which is attractive for exploring magnetic phenomena in the zero field limit. The tip material is relatively ductile and straightforward to etch. We benchmark the conventional STM and spectroscopic performance of our tips and demonstrate their spin sensitivity by measuring the two-state switching of holmium single atom magnets on MgO/Ag(100).