Fragmentation of magnetism in dipolar spin ice

Few cases exist where a system remains disordered as a gas or a liquid, even at the lowest temperatures accessible experimentally. Systems that simultaneously exhibit different order states  are even rarer.  Such a phase, “liquid” and “solid” at the same time, has been recently observed in a magnetic metamaterial, artificial spin ice.
B. Canals et al., Nat. Comm. 7, 11446  (2016);

We demonstrate the magnetic equivalent of both liquid and crystalline phases in a system which is not phase separated. This is a specially designed magnetic metamaterial called spin ice. Its peculiar magnetic properties were characterized at the Nanospectroscopy beamline of Elettra using x-ray circular dichroism photoemission electron microscopy. When imaged in real space, the magnetic configuration is essentially disordered. However, when visualized in reciprocal space, a coexistence of Bragg peaks and a diffuse background show up , thus indicating that the system is both ordered and disordered. This is not a coexistence of two out-of-equilibrium phases, but a state of matter that is both liquid and solid, everywhere in the lattice, at thermodynamic equilibrium. Interestingly,

A detailed analysis of the magnetic configuration reveals that the system acts as if each individual nanomagnet of the lattice was split into two separate components.

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Fragmentation of magnetism in artificial kagome dipolar spin ice
B. Canals, I.A. Chioar, V.-D. Nguyen, M. Hehn, D.Lacour, F. Montaigne, A. Locatelli, T.O. Menteş, B. Santos Burgos and N. Rougemaille;
Nat. Comm. 7, 11446  (2016);
doi: 10.1038/ncomms11446;

Ultima modifica il Martedì, 13 Novembre 2018 18:11