Global Formation of Topological Defects in the Multiferroic Hexagonal Manganites

Abstract

The spontaneous transformations associated with symmetry-breaking phase transitions generate domain structures and defects that may be topological in nature. The formation of these defects can be described according to the Kibble-Zurek mechanism, which provides a generic relation that applies from cosmological to interatomic lengthscales. Its verification is challenging, however, in particular at the cosmological scale where experiments are impractical. While it has been demonstrated for selected condensed-matter systems, major questions remain regarding e.g. its degree of universality. Here we develop a global Kibble-Zurek picture from the condensed-matter level. We show theoretically that a transition between two fluctuation regimes (Ginzburg and mean-field) can lead to an intermediate region with reversed scaling, and we verify experimentally this behavior for the structural transition in the series of multiferroic hexagonal manganites. Trends across the series allow us to identify additional intrinsic features of the defect formation beyond the original Kibble-Zurek paradigm. arXiv:1703.08321v1 [cond-mat.mtrl-sci]

Charged domain walls in improper ferroelectric hexagonal manganites and gallates

“…Since both cases are interesting for potential applications, such as transistors and conducting sheets or channels, we address the screening as a function of domain size -the distance between the DWs. This is particularly interesting in the h-RMnO 3 as the domain size can be controlled by the cooling rate through T C [22,39].…”

“…S5 for YGaO 3 ). Experimentally, the domain size can be controlled by the cooling rate through T C [22,39], hence both the scenarios described here, with DW distances smaller and larger than the critical distance d, can be achieved.…”

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Frequency dependent polarisation switching in h-ErMnO3

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