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Proceedings Paper

Massively degenerated ground state manifold in artificial square ice (Conference Presentation)
Author(s): Yann Perrin; Nicolas Rougemaille; Benjamin Canals
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Paper Abstract

In physics, frustration appears in a system when it is impossible to minimise all pairwise interactions simultaneously. Frustration exists in some particular rare-earth based compounds, such as spin ices [1]. Their internal frustration gives rise to unusual properties, like a residual entropy at low temperature or the presence of monopole-like excitations [2]. However, experimental techniques are unable to probe each spin individually in these compounds. In 2006, Wang and coworkers opened a new way for studying magnetically frustrated spin systems [3]. Using e-beam lithography, one can make arrays of nanomagnets with the desired design. The state of each nanomagnet can then be probed individually in real space at room temperature using magnetic imaging (eg. Magnetic Force Microscopy). In this context, the square geometry received a considerable interest, since it is closely related to condensed matter spin ice compounds. But for geometrical reasons, this system orders instead of showing a disordered low energy manifold In this contribution, we explain how to bring back the massive ground state degeneracy in the square array of nanomagnets. We present the first experimental evidence of a Coulomb phase in this system [4]. We also report the presence of magnetic monopoles defects within the Coulomb phase. This study makes a new step toward a direct study of the dynamic of monopoles excitations (e.g. creation, annihilation or diffusion processes). [1] M.J. Harris et al., Phys. Rev. Lett. 79, 2554 (1997). [2] C. Castelnovo et al., Nature 451, 7174 (2008). [3] R.F. Wang et al., Nature 439, 303 (2006). [4] Y. Perrin et al., Nature 540, 410 (2016).

Paper Details

Date Published: 21 September 2017
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Proc. SPIE 10357, Spintronics X, 103573D (21 September 2017); doi: 10.1117/12.2276988
Show Author Affiliations
Yann Perrin, CEA-LETI (France)
Nicolas Rougemaille, Institut NÉEL (France)
Benjamin Canals, Institut NÉEL (France)


Published in SPIE Proceedings Vol. 10357:
Spintronics X
Henri-Jean Drouhin; Jean-Eric Wegrowe; Manijeh Razeghi; Henri Jaffrès, Editor(s)

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