Origin of perpendicular magnetic anisotropy in ultra-thin metal films studied by in-situ neutron reflectometry

TL;DR

This study uses in-situ polarized neutron reflectometry with pulsed laser deposition to investigate the formation of perpendicular magnetic anisotropy in ultra-thin CoFeB films, revealing how bilayer structures and additional layers influence magnetic properties.

Contribution

It introduces a novel combined approach of in-situ neutron reflectometry and pulsed laser deposition to study PMA formation in ultra-thin metal films.

Findings

PMA forms in CoFeB/Mo bilayers without annealing.

Additional silicon layers can alter magnetic properties.

The method enables real-time investigation of magnetic anisotropy.

Abstract

Perpendicular magnetic anisotropy (PMA) plays an important role in different spintronic devices. The rapid development of spintronics requires a better understanding of the nature and mechanisms of the PMA formation. In our article, we demonstrate the potential of studying PMA by in-situ polarized neutron reflectometry combined with pulsed laser deposition. Using these techniques, we show the formation of out-of-plane anisotropy in thin CoFeB films (1.8 nm) with a capping Mo layer. Investigating thick (5.3 nm}) and thin (0.5 nm) molybdenum films, we demonstrate that in both cases, PMA was established in bilayer structures without any thermal annealing. Also, we demonstrate how an additional silicon layer grown over the CoFeB/Mo bilayer can critically alter the magnetic properties of the sample. Such studies are possible only through the unique combination of the growth method with the in-situ polarized neutron reflectometry measurement technique. We believe that this approach will open up broad opportunities for the development and investigation of new spintronic devices.