Modifying Critical Exponents of Magnetic Phase Transitions via Nanoscale Materials Design

Published

September 28, 2021

Author(s)

Lorenzo Fallarino, Eva Lopez Rojo, Mikel Quintana, Juan Sebastian Salcedo Gallo, Brian Kirby, Andreas Berger

Abstract

We demonstrate a nanoscale materials design path that allows us to bypass universality in thin ferromagnetic films and enables us to tune the critical exponents of ferromagnetic phase transitions in a very wide parameter range, while at the same time preserving scaling in an extended phase space near the Curie temperature. Our detailed magnetometry results reveal that single crystal CoRu alloy films, in which the predefined depth dependent exchange coupling strength follows a V-shaped profile, exhibit critical scaling behavior over many orders of magnitude. Their critical exponents, however, can be designed and controlled by modifying their specific nanoscale structures, thus demonstrating full tunability of critical behavior. The reason for this tunability and the disappearance of universality is shown to be the competing relevance of collective versus interface propagating progression of ferromagnetic phase transitions, whose balance we find to be dependent on the specifics of the underlying exchange coupling strength profile.

Citation

Physical Review Letters

Volume

127

Pub Type

Journals

Download Paper

DOI Link

Keywords

Magnetism

Citation

Fallarino, L. , Lopez Rojo, E. , Quintana, M. , Salcedo Gallo, J. , Kirby, B. and Berger, A. (2021), Modifying Critical Exponents of Magnetic Phase Transitions via Nanoscale Materials Design, Physical Review Letters, [online], https://doi.org/10.1103/PhysRevLett.127.147201 (Accessed October 10, 2025)