Fragmentation of magnetism in artificial kagome spin ice

Artificial spin ices (ASI) are systems designed to explore the intriguing physics observed in magnetically frustrated materials. Generally fabricated by using lithography techniques, they offer almost infinite possibilities to construct a wide variety of spin models which can be accessed experimentally in a controlled manner.

Here, we investigate magnetic frustration effects in a thermally active kagome ASI. The magnetic configurations we image reveal the fingerprints of a spin fragmentation process. This process, predicted theoretically, corresponds to a splitting of the spin degree of freedom into two independent sectors [1]. In some cases, one given classical spin can belong simultaneously to an ordered magnetic configuration and to a highly disordered one. In our experiment, the first sector is identified as an incipient antiferromagnetic crystal of an all-in/all-out spin configuration, in which spins carry 1/3 of their total magnetic moment, while the second sector corresponds to a diffuse organization of the remaining fragmented spins carrying 2/3 and 4/3 magnetic moments. We thus provide the first experimental evidence of spin fragmentation in ASI [2].

[1] M. E. Brooks-Bartlett et al., Phys. Rev. X 4, 011007 (2014).
[2] B. Canals et al., Nat. Commun. 7, 11446 (2016).