Ezio Iacocca publishes the dispersive hydrodynamic formulation of thin film ferromagnets in Physical Review Letters

Solid-state magnetic materials are intrinsically dynamic, stemming from the forces that act at the nanoscale and favor a macroscopic, collective order. In the case of a thin film ferromagnet, effectively a two dimensional magnetic medium, the equation describing its can be cast as a set of dispersive hydrodynamic equations. Remarkably, this means that a solid-state ferromagnet behaves like a fluid! Not just any fluid, however. Thin film ferromagnets are peculiar in which their effective density is not a conserved quantity. As a consequence, these materials break Gaillean invariance, i.e., the physics are reference-frame-dependent, an effect typically associated with relativity.

This was demonstrated in the paper Breaking of Galilean invariance in the hydrodynamic formulation of thin film ferromagnets, co-authored by Dr. Iacocca and Prof. Hoefer in collaboration with Dr. Silva from NIST, and recently published in Physical Review Letters. Furthermore, it is shown that thin film ferromagnets also exhibit familiar fluid properties including a speed of sound and an associated Mach number identifying supersonic flow conditions. This formulation opens a new perspective to interpret magnetic dynamics and establishes a connection to the rich area of dispersive hydrodynamics.

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