Compact pulsed laser deposition system for in-situ polarized neutron reflectometry

TL;DR

This paper presents a novel compact system combining pulsed laser deposition with in-situ polarized neutron reflectometry, enabling real-time magnetic characterization of thin films during growth and post-annealing.

Contribution

It introduces the first integrated PLD and in-situ PNR setup, allowing detailed magnetic analysis of CoFeB/Mo thin films during fabrication and thermal treatment.

Findings

Observation of magnetic property evolution during multilayer growth.

Detection of perpendicular magnetic anisotropy at CoFeB/Mo interfaces.

Confirmation of increased in-plane magnetization after annealing.

Abstract

The development of ferromagnet/heavy metal thin-film structures, such as CoFeB/Mo, with spin-orbit interaction requires advanced methods for their production and study. Polarized neutron reflectometry (PNR) provides unique insights into the evolution of magnetic properties, especially when applied in-situ during the growth process. Pulsed laser deposition (PLD) is a versatile method for producing magnetic thin films, and combining PLD with in-situ PNR measurements offers new possibilities for their investigation. In this work, we developed a compact vacuum chamber integrated into the neutron instrument, enabling step-by-step deposition and in-situ PNR measurements. A multilayer Mo/[CoFeB/Mo]12 structure was grown, and neutron reflectivity curves measured after each cycle revealed the gradual evolution of sample properties. A weak magnetic field response suggested the potential formation of perpendicular magnetic anisotropy (PMA) at CoFeB/Mo interfaces. Additionally, a single CoFeB film was annealed up to 450{\deg}C, followed by the deposition of a ~5 {\AA} Mo layer. PNR measurements in magnetic fields of 0.01 T and 0.75 T showed a significant increase in in-plane magnetization, confirming PMA formation. Thus, we demonstrate the first successful operation of a combined PLD and in-situ PNR system, showcasing its capabilities for characterizing single-layer CoFeB and multilayer CoFeB/Mo thin-film structures.