Topology and Disorder, Friends or Foes?

Introduction

Topological properties often depend on symmetry, magnetic texture, and spin-orbit coupling. That can make disorder sound like a threat: if local structure or local magnetism deviates from the ideal model, will the topological response disappear?

In real quantum materials, the answer is more interesting. Disorder is not always random damage. Short-range correlations, local distortions, and domain textures can become part of the mechanism that controls transport.

Disorder as Information

For materials such as Mn₃Sn, the anomalous Hall effect is usually discussed through the lens of long-range magnetic symmetry and Berry curvature. But neutron total scattering and local modeling let us ask a complementary question:

What local magnetic correlations are present before they become visible as long-range order?

That question matters because local correlations can influence how a material approaches a topological transition, how robust its transport response is, and how much of the observed behavior is controlled by nanoscale texture rather than only the average crystal structure.

Computational Angle

This is where the problem becomes a data-science problem as much as a physics problem. Total-scattering experiments produce information-rich but indirect measurements. Extracting meaning requires inverse modeling, constrained optimization, uncertainty checks, and careful comparison between simulated and observed signals.

The workflow is close in spirit to many industrial modeling problems:

• the signal is noisy and indirect,
• the model is high-dimensional,
• the interpretation depends on domain constraints,
• and the result needs to be communicated clearly enough to guide decisions.

Takeaway

Disorder and topology are not automatically enemies. In correlated quantum materials, local disorder can be a hidden design variable. The technical challenge is building tools that can detect, model, and validate that hidden structure.

References

• Selected related papers are listed on the publications page.