Signatures of Fluctuation-Driven Magnetic Topological Charge in Pt-Ferromagnetic Insulator Bilayers

Chiral magnetic textures are of fundamental interest for studying exotic spin behavior, but also promising for the development of energy-efficient memory and logic devices. Recent computational work has suggested that in contrast to well-studied static chiral textures like skyrmions, there exists dynamic fluctuation-driven magnetic chirality even in the absence of long-range magnetic order. Here, we present definitive magnetotransport signatures of fluctuation-driven chirality in a model material system of Pt/Li_{0.5}Al_{1.0}Fe_{1.5}O_{4} (LAFO) bilayers, where LAFO is a ferromagnetic insulator. We establish a fluctuation-driven origin for the magnetic chirality by observing a strong correlation between the onset of the topological Hall effect and the destruction of magnetic order. Corroborated by Monte Carlo simulations, we develop a rigorous analytical framework to gain a first-principles understanding of scaling behaviors in the transport data. Our results bring novel insights to fluctuation-driven chirality and analysis of magnetotransport data.