Resonant pinning spectroscopy with spin-vortex pairs

TL;DR

This paper introduces resonant pinning spectroscopy for magnetic vortex pairs, demonstrating how microwave excitation can selectively pin or depin cores based on their eigenmodes, enabling potential multi-state memory and defect characterization.

Contribution

It presents a novel resonant spectroscopy technique for vortex pairs that allows selective control and characterization of magnetic states and defects.

Findings

Resonant frequencies differ between pinned and depinned states.

Microwave excitation can induce controlled pinning or depinning.

Technique can be used for nanoscale defect characterization.

Abstract

Vortex pairs in magnetic nanopillars with strongly coupled cores and pinning of one of the cores by a morphological defect, are used to perform resonant pinning spectroscopy, in which a microwave excitation applied to the nanopillar produces pinning or depinning of the cores only when the excitation is in resonance with the rotational or gyrational eigenmodes of the specific initial state of the core-core pair. The shift in the eigenmode frequencies between the pinned and depinned states is determined experimentally and explained theoretically, and illustrates the potential for multi-core spin-vortex memory with resonant writing of information on to various stable vortex pair states. Further, it is shown how the same resonant spectroscopy techniques applied to a vortex pair can be used as a sensitive nanoscale probe for characterizing morphological defects in magnetic films.