# Altermagnetic surface states: towards the observation and utilization of altermagnetism in thin films, interfaces and topological materials

**Authors:** Raghottam M Sattigeri, Giuseppe Cuono, Carmine Autieri  
**arXiv:** [2307.10146](https://arxiv.org/abs/2307.10146)  
**Date:** 2023-07-19  
**Summary page:** https://www.summarizepaper.com/en/paper/2307.10146v2/

## Key points

- Researchers investigate altermagnetism and its influence on electronic states
- Anticipation of altermagnetic surface states on specific surface orientations within the 3D Brillouin zone
- Focus on tetragonal, orthorhombic, and hexagonal space groups
- Analysis of 2D projected Brillouin zone to identify spin splittings convergence points
- Certain surface orientations impervious to altermagnetism while persisting on others influenced by magnetic order
- Activation of altermagnetism by applying an electric field perpendicular to a "blind" surface
- Guidance on cleaving surfaces to preserve altermagnetic effects in thin films
- Potential observation of non-relativistic altermagnetic spin splittings through techniques like spin-resolved ARPES
- Exploration of interfacing altermagnetism with other collective modes and impact on trivial and topological surface states

## Summary

In this study, the researchers investigate altermagnetism and its influence on electronic states. By examining specific k-paths within the 3D Brillouin zone, they anticipate the presence of altermagnetic surface states on certain surface orientations. The investigation focuses on three representative space groups: tetragonal, orthorhombic, and hexagonal. Through calculations of the 2D projected Brillouin zone from the 3D counterpart, the researchers analyze surfaces alongside their respective 2D Brillouin zones to identify where spin splittings with opposite signs converge. This can potentially nullify altermagnetic properties. The findings reveal that certain surface orientations are impervious to altermagnetism while it persists on others. This phenomenon is influenced by magnetic order. Additionally, applying an electric field perpendicular to a "blind" surface can activate altermagnetism. This insight offers guidance on which surfaces to cleave in order to preserve altermagnetic effects in thin films. It also paves the way for observing non-relativistic altermagnetic spin splittings through techniques like spin-resolved ARPES. Furthermore, this research opens up avenues for interfacing altermagnetism with other collective modes and exploring its impact on both trivial and topological surface states. By shedding light on how different surface orientations interact with altermagnetism and providing strategies for enhancing its presence through external stimuli, this study contributes valuable insights to the fields of condensed matter physics and materials science.