Scale-invariant magnetic textures in the strongly correlated oxide NdNiO<sub>3</sub>.

Li, Jiarui; Pelliciari, Jonathan; Mazzoli, Claudio; Catalano, Sara; Simmons, Forrest; Sadowski, Jerzy T; Levitan, Abraham; Gibert, Marta et al. · Nat Commun · 2019

basic_science · Level V

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Abstract

Strongly correlated quantum solids are characterized by an inherently granular electronic fabric, with spatial patterns that can span multiple length scales in proximity to a critical point. Here, we use a resonant magnetic X-ray scattering nanoprobe with sub-100 nm spatial resolution to directly visualize the texture of antiferromagnetic domains in NdNiO<sub>3</sub>. Surprisingly, our measurements reveal a highly textured magnetic fabric, which we show to be robust and nonvolatile even after thermal erasure across its ordering temperature. The scale-free distribution of antiferromagnetic domains and its non-integral dimensionality point to a hitherto-unobserved magnetic fractal geometry in this system. These scale-invariant textures directly reflect the continuous nature of the magnetic transition and the proximity of this system to a critical point. The present study not only exposes the near-critical behavior in rare earth nickelates but also underscores the potential for X-ray scattering nanoprobes to image the multiscale signatures of criticality near a critical point.