Emergent Rotational Symmetries in Disordered Magnetic Domain Patterns

Run Su, Keoki A. Seu, Daniel Parks, Jimmy J. Kan, Eric E. Fullerton, Sujoy Roy, and Stephen D. Kevan

Phys. Rev. Lett. 107, 257204 – Published 16 December 2011

Abstract

Uniaxial systems often form labyrinthine domains that exhibit short-range order but are macroscopically isotropic and would not be expected to exhibit precise symmetries. However, their underlying frustration results in a multitude of metastable configurations of comparable energy, and driving such a system externally might lead to pattern formation. We find that soft x-ray speckle diffraction patterns of the labyrinthine domains in $CoPd / IrMn$ heterostructures reveal a diverse array of hidden rotational symmetries about the magnetization axis, thereby suggesting an unusual form of emergent order in an otherwise disordered system. These symmetries depend on applied magnetic field, magnetization history, and scattering wave vector. Maps of rotational symmetry exhibit intriguing structures that can be controlled by manipulating the applied magnetic field in concert with the exchange bias condition.

Received 26 August 2011

DOI:https://doi.org/10.1103/PhysRevLett.107.257204

Authors & Affiliations

Run Su^1,2, Keoki A. Seu^1,2, Daniel Parks^1,2, Jimmy J. Kan³, Eric E. Fullerton³, Sujoy Roy¹, and Stephen D. Kevan^2,*

¹Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
²Department of Physics, University of Oregon, Eugene, Oregon 97403, USA
³Electrical and Computer Engineering, University of California, San Diego, California 92093, USA