Kavli Affiliate: Darrell G. Schlom
| First 5 Authors: Shashank Kumar Ojha, Pratap Pal, Sergei Prokhorenko, Sajid Husain, Maya Ramesh
| Summary:
Pattern formation in spin systems with continuous-rotational symmetry (CRS)
provides a powerful platform to study emergent complex magnetic phases and
topological defects in condensed-matter physics. However, its understanding and
correlation with unconventional magnetic order along with high-resolution
nanoscale imaging is challenging. Here, we employ scanning NV magnetometry to
unveil the morphogenesis of spin cycloids at both the local and global scales
within a single ferroelectric domain of (111)-oriented BiFeO$_3$ (which is a
non-collinear antiferromagnet), resulting in formation of a glassy labyrinthine
pattern. We find that the domains of locally oriented cycloids are
interconnected by an array of topological defects and exhibit isotropic energy
landscape predicted by first-principles calculations. We propose that the CRS
of spin-cycloid propagation directions within the (111) drives the formation of
the labyrinthine pattern and the associated topological defects such as
antiferromagnetic skyrmions. Unexpectedly, reversing the as-grown ferroelectric
polarization from [$bar{1}$$bar{1}$$bar{1}$] to [111] induces a magnetic
phase transition, destroying the labyrinthine pattern and producing a
deterministic non-volatile non cycloidal, uniformly magnetized state. These
findings highlight that (111)-oriented BiFeO$_3$ is not only important for
studying the fascinating subject of pattern formation but could also be
utilized as an ideal platform for integrating novel topological defects in the
field of antiferromagnetic spintronics.
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