# Identification of topological superconductivity in magnetic impurity systems using bulk spin-polarization

## TL;DR

This paper demonstrates that bulk spin-polarization measurements in magnetic impurity systems can reliably identify topological superconductivity and phase transitions, providing an alternative to boundary state detection.

## Contribution

It introduces a method to detect topological phases via interior spin-polarization changes, independent of boundary Majorana states.

## Key findings

- Spin-polarization changes sign at topological phase transition.
- Applicable to both 1D impurity chains and 2D islands.
- Provides an alternative topological phase detection method.

## Abstract

Magnetic impurities on the surface of spin-orbit coupled but otherwise conventional superconductors provide a promising way to engineer topological superconductors with Majorana bound states as for boundary modes. In this work, we show that the spin-polarization in the interior of both one-dimensional impurity chains and two-dimensional islands can be used to determine the topological phase, as it changes sign exactly at the topological phase transition. This offers an independent probe of the topological phase, beyond the zero-energy Majorana bound states appearing at the boundaries of the topological region.