Theoretical study of the role of the tip in enhancing the sensitivity of differential conductance tunneling spectroscopy on magnetic surfaces

TL;DR

This study uses a simple theoretical model to analyze how tip magnetization and electronic structure influence the sensitivity of differential conductance tunneling spectroscopy on magnetic surfaces, highlighting ways to enhance detection capabilities.

Contribution

It introduces a theoretical framework that accounts for tip electronic structure and energy-dependent vacuum decay, enabling better understanding and tuning of STS sensitivity on magnetic surfaces.

Findings

Tip magnetization and electronic structure significantly affect dI/dV spectra.

Choosing appropriate magnetic tips can enhance STS sensitivity.

Effective spin-polarization governs the sensitivity enhancement.

Abstract

Based on a simple model for spin-polarized scanning tunneling spectroscopy (SP-STS) we study how tip magnetization and electronic structure affects the differential conductance (dI/dV) tunneling spectrum of an Fe(001) surface. We take into account energy dependence of the vacuum decay of electron states, and tip electronic structure either using an ideal model or based on ab initio electronic structure calculation. In the STS approach, topographic and magnetic contributions to dI/dV can clearly be distinguished and analyzed separately. Our results suggest that the sensitivity of STS on a magnetic sample can be tuned and even enhanced by choosing the appropriate magnetic tip and bias setpoint, and the effect is governed by the effective spin-polarization.