Memory effect and magnetocrystalline anisotropy impact on the surface magnetic domains of magnetite(001)

Journal Article · 16 April 2018 · Scientific Reports

DOI: https://doi.org/10.1038/s41598-018-24160-1 · OSTI ID:1592411

Martín-García, Laura ^[1]; Chen, Gong ^[2]; Montaña, Yaiza ^[1]; Mascaraque, Arantzazu ^[3]; Pabón, Beatriz M. ^[3]; Schmid, Andreas K. ^[2]; de la Figuera, Juan  ^[1]

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1. Spanish National Research Council (CSIC), Madrid (Spain)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
3. Univ. Complutense, Madrid (Spain); Unidad Asociada IQFR(CSIC)-UCM, Madrid (Spain)

The structure of magnetic domains, i.e. regions of uniform magnetization separated by domain walls, depends on the balance of competing interactions present in ferromagnetic (or ferrimagnetic) materials. When these interactions change then domain configurations also change as a result. Magnetite provides a good test bench to study these effects, as its magnetocrystalline anisotropy varies significantly with temperature. Using spin-polarized electron microscopy to map the micromagnetic domain structure in the (001) surface of a macroscopic magnetite crystal (~1 cm size) shows complex domain patterns with characteristic length-scales in the micrometer range and highly temperature dependent domain geometries. Although heating above the Curie temperature erases the domain patterns completely, cooling down reproduces domain patterns not only in terms of general characteristics: instead, complex microscopic domain geometries are reproduced in almost perfect fidelity between heating cycles. A possible explanation of the origin of the high-fidelity reproducibility is suggested to be a combination of the presence of hematite inclusions that lock bulk domains, together with the strong effect of the first order magnetocrystalline anisotropy which competes with the shape anisotropy to give rise to the observed complex patterns.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); Ministry of Economic Affairs and Digital Transformation of Spain (MINECO)
• Grant/Contract Number: AC02-05CH11231; BES-2013-063396
• OSTI ID: 1592411
• Journal Information: Scientific Reports, Vol. 8, Issue 1; ISSN 2045-2322
• Publisher: Nature Publishing GroupCopyright Statement
• Country of Publication: United States
• Language: English