# Probing Magnetic Excitations and Correlations in Single and Coupled Spin Systems with Scanning Tunneling Spectroscopy

## TL;DR

This paper reviews how low-temperature scanning tunneling spectroscopy reveals magnetic excitations and correlations in single and coupled spin systems, elucidating quantum states and interactions at the atomic level.

## Contribution

It introduces advanced spectroscopic analysis of complex bipartite and spin-chain systems, highlighting their quantum interactions and emergent states.

## Key findings

- Identification of magnetic anisotropy effects in spectra
- Detection of interatomic entanglement in spin chains
- Characterization of quantum states in coupled spin systems

## Abstract

Spectroscopic measurements with low-temperature scanning tunneling microscopes have been used very successfully for studying not only individual atomic or molecular spins on surfaces but also complexly designed coupled systems. The symmetry breaking of the supporting surface induces magnetic anisotropy which lead to characteristic fingerprints in the spectrum of the differential conductance and can be well understood with simple model Hamiltonians. Furthermore, correlated many-particle states can emerge due to the interaction with itinerant electrons of the electrodes, making these systems ideal prototypical quantum systems. In this manuscript more complex bipartite and spin-chains will be discussed additionally. Their spectra enable to determine precisely the nature of the interactions between the spins which can lead to the formation of new quantum states which emerge by interatomic entanglement.