Quantum material’s giant stretch confirms 100-year-old prediction

Researchers at the University of St Andrews have pushed the boundaries of nanoscale imaging to confirm a physics prediction almost 100 years old - thanks to cutting-edge ultra-low temperature scanning tunneling microscopy (STM).

In a study [1] published in Nature Physics, the team investigated magnetoelastic coupling - the tiny way materials change shape under magnetic fields - in a surprising candidate: a transition metal oxide. These oxides are central to advanced materials like high-temperature superconductors, but the magnetoelastic effects here were far larger than expected.

Using bespoke STM instruments housed in ultra-quiet, ultra-stable vibration-free labs, the scientists detected atomic-scale shifts as tiny as a few hundred femtometres - that’s a millionth of a nanometre, or roughly one quadrillionth of a meter. This extraordinary precision allowed them to observe how subtle changes in magnetic alignment dramatically stretch or contract the material’s crystal lattice.

The findings confirm the Bethe-Slater curve, a foundational theory from the 1930s describing the relationship between magnetism and atomic spacing - but in this complex oxide material, something remarkable happened. The measured structural changes were much larger than existing models predicted, revealing new physics at the atomic scale.

Lead researcher Dr Carolina Marques explained: “Our STM setup let us separate the magnetization of the surface layer from the bulk material, enabling direct measurement of electronic and structural changes with unprecedented precision. This could open the door to innovative ways of reading magnetic states electronically or structurally - a breakthrough for future data storage technology.”

Professor Peter Wahl added: “This work not only validates nearly a century of theory but also highlights the intricate dance between structure, electron correlations, and magnetism in quantum materials. Mastering these effects through advanced microscopy could accelerate the development of greener, more stable superconductors and novel quantum devices.”

More information online

1.     'Emergent exchange-driven giant magnetoelastic coupling in a correlated itinerant ferromagnet'  published in Nature Physics