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Magnetic and electrical transport signatures of uncompensated moments in epitaxial thin films of the noncollinear antiferromagnet Mn3Ir

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posted on 2024-06-06, 15:18 authored by James M Taylor, Edouard Lesne, Anastasios Markou, Fasil DejeneFasil Dejene, Pranava Keerthi Sivakumar, Simon Pöllath, Kumari Gaurav Rana, Neeraj Kumar, Chen Luo, Hanjo Ryll, Florin Radu, Florian Kronast, Peter Werner, Christian H Back, Claudia Felser, Stuart SP Parkin
Noncollinear antiferromagnets, with either an L12 cubic crystal lattice (e.g., Mn3Ir and Mn3Pt) or a D019 hexagonal structure (e.g., Mn3Sn and Mn3Ge), exhibit a number of phenomena of interest to topological spintronics. Among the cubic systems, for example, tetragonally distorted Mn3Pt exhibits an intrinsic anomalous Hall effect (AHE). However, Mn3Pt only enters a noncollinear magnetic phase close to the stoichiometric composition and at suitably large thicknesses. Therefore, we turn our attention to Mn3Ir, the material of choice for use in exchange bias heterostructures. In this letter, we investigate the magnetic and electrical transport properties of epitaxially grown, face-centered-cubic γ-Mn3Ir thin films with (111) crystal orientation. Relaxed films of 10 nm thickness exhibit an ordinary Hall effect, with a hole-type carrier concentration of (1.500 ± 0.002) × 1023 cm−3. On the other hand, TEM characterization demonstrates that ultrathin 3 nm films grow with significant in-plane tensile strain. This may explain a small net magnetic moment, observed at low temperatures, shown by X-ray magnetic circular dichroism spectroscopy to arise from uncompensated Mn spins. Being of the order of 0.02 μB/atom, this dominates electrical transport behavior, leading to a small AHE and negative magnetoresistance. These results are discussed in terms of crystal microstructure and chiral domain behavior, with spatially resolved XML(C)D-PEEM supporting the conclusion that small antiferromagnetic domains, <20 nm in size, with differing chirality account for the absence of observed Berry curvature driven magnetotransport effects.

Funding

German Federal Ministry for Education and Research (BMBF 05K10PC2, 05K10WR1, 05K10KE1)

HZB

Antiferromagntic spintronics

European Commission

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History

School

  • Science

Department

  • Physics

Published in

Applied Physics Letters

Volume

115

Issue

6

Publisher

AIP Publishing

Version

  • AM (Accepted Manuscript)

Rights holder

© AIP Publishing

Publisher statement

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in James M. Taylor, Edouard Lesne, Anastasios Markou, Fasil Kidane Dejene, Pranava Keerthi Sivakumar, Simon Pöllath, Kumari Gaurav Rana, Neeraj Kumar, Chen Luo, Hanjo Ryll, Florin Radu, Florian Kronast, Peter Werner, Christian H. Back, Claudia Felser, Stuart S. P. Parkin; Magnetic and electrical transport signatures of uncompensated moments in epitaxial thin films of the noncollinear antiferromagnet Mn3Ir. Appl. Phys. Lett. 5 August 2019; 115 (6): 062403 and may be found at https://doi.org/10.1063/1.5099428.

Acceptance date

2019-07-05

Publication date

2019-08-05

Copyright date

2019

ISSN

0003-6951

eISSN

1077-3118

Language

  • en

Depositor

Dr Fasil Dejene. Deposit date: 7 May 2024

Article number

062403

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