Interdimensional universality of dynamic interfaces

Abstract

Despite the complexity and diversity of nature, there exists universality in the form of critical scaling laws among various dissimilar systems and processes such as stock markets, earthquakes, crackling noise, lung inflation and vortices in superconductors. This universality is mainly independent of the microscopic details, depending only on the symmetry and dimension of the system. Exploring how universality is affected by the system dimensions is an important unresolved problem. Here we demonstrate experimentally that universality persists even at a dimensionality crossover in ferromagnetic nanowires. As the wire width decreases, the magnetic domain wall dynamics changes from elastic creep in two dimensions to a particle-like stochastic behaviour in one dimension. Applying finite-size scaling, we find that all our experimental data in one and two dimensions (including the crossover regime) collapse onto a single curve, signalling universality at the criticality transition. The crossover to the one-dimensional regime occurs at a few hundred nanometres, corresponding to the integration scale for modern nanodevices.

Electric-field control of magnetic domain-wall velocity in ultrathin cobalt with perpendicular magnetization

“…The observed significant change in the velocity was found to be due to the electrical modulation of the effective energy barrier for the thermally activated DW creep motion 18,19,[38][39][40][41] .…”

Precise control of domain wall injection and pinning using helium and gallium focused ion beams

“…However, this approach is not very elegant, as the magnetic field needed for DW creation is not controlled and nucleation may occur at unintended spots. Alternative approaches include thermomagnetic writing with a laser spot 10 or using the Oersted field generated by a nearby current pulse line, but these methods pose restrictions to the experimental environment and sample design.…”

Spatially periodic domain wall pinning potentials: Asymmetric pinning and dipolar biasing

“…This offers an attractive way to study the effects of co-existing periodic 61,62 and disordered 24 pinning potentials on domain wall motion, especially when noting the applicability of domain walls in ultrathin Pt/Co/Pt layers to the rich, fundamen-tal problem of elastic interface dynamics in disordered media [24][25][26] .…”

“…This means that it is possible to study the effects of two independent but coexistent domain wall pinning potentials, one periodic, the other disordered. Since domain walls in Pt/Co/Pt films are described well by general theories for elastic interface motion in disordered systems [24][25][26] , there is a fundamental interest in creating model experimental systems for studying interface motion where pinning effects can be controllably modified.…”