Zero-point quantum swing of magnetic couples

TL;DR

This paper demonstrates that zero-point quantum spin-fluctuations critically influence magnetic interactions and stability in nanostructures, providing insights for designing advanced magnetic nanodevices.

Contribution

It introduces a quantum fluctuation-based framework to accurately predict magnetic interactions, bridging the gap between theory and experiment in nanomagnetism.

Findings

Zero-point spin-fluctuations significantly affect magnetic exchange interactions.

Quantum fluctuations improve the accuracy of theoretical predictions.

They promote non-collinearity and stability of chiral magnetic textures like skyrmions.

Abstract

Quantum fluctuations are ubiquitous in physics. Ranging from conventional examples like the harmonic oscillator to intricate theories on the origin of the universe, they alter virtually all aspects of matter -- including superconductivity, phase transitions and nanoscale processes. As a rule of thumb, the smaller the object, the larger their impact. This poses a serious challenge to modern nanotechnology, which aims total control via atom-by-atom engineered devices. In magnetic nanostructures, high stability of the magnetic signal is crucial when targeting realistic applications in information technology, e.g. miniaturized bits. Here, we demonstrate that zero-point spin-fluctuations are paramount in determining the fundamental magnetic exchange interactions that dictate the nature and stability of the magnetic state. Hinging on the fluctuation-dissipation theorem, we establish that quantum fluctuations correctly account for the large overestimation of the interactions as obtained from conventional static first-principles frameworks, filling in a crucial gap between theory and experiment [1,2]. Our analysis further reveals that zero-point spin-fluctuations tend to promote the non-collinearity and stability of chiral magnetic textures such as skyrmions -- a counter-intuitive quantum effect that inspires practical guidelines for designing disruptive nanodevices.