The most powerful magnets for high temperature applications are Sm-Co-based alloys with a microstructure that combines magnetically soft and hard regions. The microstructure consists of a dense domain-wall-pinning network that endows the material with remarkable magnetic hardness. A precise understanding of the coupling between magnetism and microstructure is essential for enhancing the performance of Sm-Co magnets, but experiments and theory have not yet converged to a unified model. Here, we combine transmission electron microscopy, atom probe tomography, and nanometer-resolution off-axis electron holography with micromagnetic simulations to show that the magnetization processes in Sm-Co magnets result from an interplay between curling instabilities and pinning effects at the intersections between magnetically soft and hard regions. We also find that topologically non-trivial magnetic domains separated by a complex network of domain walls play a key role in the magnetic state. Our findings reveal a previously hidden aspect of magnetism and provide insight into the full potential of high-performance magnetic materials.
@article{arxiv.1901.01922,
title = {Unconventional magnetization textures and domain-wall pinning in Sm-Co magnets},
author = {Leonardo Pierobon and András Kovács and Robin E. Schäublin and S. S. A. Gerstl and J. Caron and Urs Wyss and Rafal E. Dunin-Borkowski and Jörg F. Löffler and Michalis Charilaou},
journal= {arXiv preprint arXiv:1901.01922},
year = {2020}
}