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Phase coexistence and transitions between antiferromagnetic and ferromagnetic states in a synthetic antiferromagnet

DOI: 10.1103/PhysRevB.109.134437 DOI Help

Authors: C. E. A. Barker (University of Leeds; National Physical Laboratory (UK)) , K. Fallon (University of Glasgow) , C. Barton (National Physical Laboratory (UK)) , E. Haltz (University of Leeds) , T. P. Almeida (University of Glasgow) , S. Villa (University of Glasgow) , C. Kirkbride (University of Glasgow) , F. Maccherozzi (Diamond Light Source) , B. Sarpi (Diamond Light Source) , S. S. Dhesi (Diamond Light Source) , D. Mcgrouther (University of Glasgow) , S. Mcvitie (University of Glasgow) , T. A. Moore (University of Leeds) , O. Kazakova (National Physical Laboratory (UK)) , C. H. Marrows (University of Leeds)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 109

State: Published (Approved)
Published: April 2024
Diamond Proposal Number(s): 28586

Open Access Open Access

Abstract: In synthetic antiferromagnets (SAFs), antiferromagnetic (AFM) order and synthesis using conventional sputtering techniques is combined to produce systems that are advantageous for spintronics applications. Here we present the preparation and study of SAF multilayers possessing both perpendicular magnetic anisotropy and the Dzyaloshinskii-Moriya interaction. The multilayers have an antiferromagnetically aligned ground state but can be forced into a full ferromagnetic (FM) alignment by applying an out-of-plane field ∼ 100 mT. We study the spin textures in these multilayers in their ground state as well as around the transition point between the AFM and FM states at fields ∼ 40 mT by imaging the spin textures using complementary methods: photoemission electron, magnetic force, and Lorentz transmission electron microscopies. The transformation into a FM state by field proceeds by a nucleation and growth process, where skyrmionic nuclei form and then broaden into regions containing a ferromagnetically aligned labyrinth pattern that eventually occupies the whole film. Remarkably, this process occurs without any significant change in the net magnetic moment of the multilayer. The mix of antiferromagnetically and ferromagnetically aligned regions on the micron scale in the middle of this transition is reminiscent of a first-order phase transition that exhibits phase coexistence. These results are important for guiding the design of spintronic devices whose operation is based on spin textures in perpendicularly magnetized SAFs.

Journal Keywords: Skyrmions; Synthetic antiferromagnetic multilayers; Lorentz microscopy; Magnetic force microscopy; Photoelectron emission microscopy

Diamond Keywords: Antiferromagnetism; Skyrmions; Spintronics; Data Storage

Subject Areas: Materials, Physics, Information and Communication Technology

Instruments: I06-Nanoscience (XPEEM)

Added On: 01/05/2024 11:50


Discipline Tags:

Quantum Materials Physics Hard condensed matter - structures Electronics Components & Micro-systems Information & Communication Technologies Magnetism Materials Science

Technical Tags:

Microscopy Spectroscopy Electron Microscopy (EM) PhotoEmmission Electron Microscopy (PEEM) Circular Dichroism (CD) X-ray Magnetic Circular Dichroism (XMCD)