1
|
Köhler T, Feoktystov A, Petracic O, Nandakumaran N, Cervellino A, Brückel T. Signature of antiphase boundaries in iron oxide nanoparticles. J Appl Crystallogr 2021; 54:1719-1729. [PMID: 34963764 PMCID: PMC8662974 DOI: 10.1107/s1600576721010128] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 09/29/2021] [Indexed: 11/10/2022] Open
Abstract
Iron oxide nanoparticles find a wide variety of applications, including targeted drug delivery and hyperthermia in advanced cancer treatment methods. An important property of these particles is their maximum net magnetization, which has been repeatedly reported to be drastically lower than the bulk reference value. Previous studies have shown that planar lattice defects known as antiphase boundaries (APBs) have an important influence on the particle magnetization. The influence of APBs on the atomic spin structure of nanoparticles with the γ-Fe2O3 composition is examined via Monte Carlo simulations, explicitly considering dipole-dipole interactions between the magnetic moments that have previously only been approximated. For a single APB passing through the particle centre, a reduction in the magnetization of 3.9% (for 9 nm particles) to 7.9% (for 5 nm particles) is found in saturation fields of 1.5 T compared with a particle without this defect. Additionally, on the basis of Debye scattering equation simulations, the influence of APBs on X-ray powder diffraction patterns is shown. The Fourier transform of the APB peak profile is developed to be used in a whole powder pattern modelling approach to determine the presence of APBs and quantify them by fits to powder diffraction patterns. This is demonstrated on experimental data, where it could be shown that the number of APBs is related to the observed reduction in magnetization.
Collapse
Affiliation(s)
- Tobias Köhler
- Jülich Centre for Neutron Science JCNS at Heinz Maier-Leibnitz Zentrum MLZ, Forschungszentrum Jülich GmbH, 85748 Garching, Germany
- Jülich Centre for Neutron Science JCNS-2 and Peter Grünberg Institute PGI-4, JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Lehrstuhl für Experimentalphysik IV C, RWTH Aachen University, 52056 Aachen, Germany
| | - Artem Feoktystov
- Jülich Centre for Neutron Science JCNS at Heinz Maier-Leibnitz Zentrum MLZ, Forschungszentrum Jülich GmbH, 85748 Garching, Germany
| | - Oleg Petracic
- Jülich Centre for Neutron Science JCNS-2 and Peter Grünberg Institute PGI-4, JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Nileena Nandakumaran
- Jülich Centre for Neutron Science JCNS-2 and Peter Grünberg Institute PGI-4, JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Lehrstuhl für Experimentalphysik IV C, RWTH Aachen University, 52056 Aachen, Germany
| | - Antonio Cervellino
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Thomas Brückel
- Jülich Centre for Neutron Science JCNS-2 and Peter Grünberg Institute PGI-4, JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Lehrstuhl für Experimentalphysik IV C, RWTH Aachen University, 52056 Aachen, Germany
| |
Collapse
|
2
|
Moreno R, Jenkins S, Skeparovski A, Nedelkoski Z, Gerber A, Lazarov VK, Evans RFL. Role of anti-phase boundaries in the formation of magnetic domains in magnetite thin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:175802. [PMID: 33530069 DOI: 10.1088/1361-648x/abe26c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 02/02/2021] [Indexed: 06/12/2023]
Abstract
Anti-phase boundaries (APBs) are structural defects which have been shown to be responsible for the anomalous magnetic behavior observed in different nanostructures. Understanding their properties is crucial in order to use them to tune the properties of magnetic materials by growing APBs in a controlled way since their density strongly depends on the synthesis method. In this work we investigate their influence on magnetite (Fe3O4) thin films by considering an atomistic spin model, focussing our study on the role that the exchange interactions play across the APB interface. We conclude that the main atypical features reported experimentally in this material are well described by the model we propose here, confirming the new exchange interactions created in the APB as the responsible for this deviation from bulk properties.
Collapse
Affiliation(s)
- Roberto Moreno
- Department of Physics, University of York, Heslington, York, YO10 5DD, United Kingdom
- Earth and Planetary Science, School of Geosciences, University of Edinburgh, Edinburgh EH9 3FE, United Kingdom
| | - Sarah Jenkins
- Department of Physics, University of York, Heslington, York, YO10 5DD, United Kingdom
| | - Aleksandar Skeparovski
- Institute of Physics, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, Arhimedova 3, 1000 Skopje, Macedonia
| | - Zlatko Nedelkoski
- Faculty of Technical Sciences, University Mother Theresa, Mirche Acev No. 4, Skopje 1000, Macedonia
| | - Alexander Gerber
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
| | - Vlado K Lazarov
- Department of Physics, University of York, Heslington, York, YO10 5DD, United Kingdom
| | - Richard F L Evans
- Department of Physics, University of York, Heslington, York, YO10 5DD, United Kingdom
| |
Collapse
|
3
|
Nedelkoski Z, Kepaptsoglou D, Lari L, Wen T, Booth RA, Oberdick SD, Galindo PL, Ramasse QM, Evans RFL, Majetich S, Lazarov VK. Origin of reduced magnetization and domain formation in small magnetite nanoparticles. Sci Rep 2017; 7:45997. [PMID: 28393876 PMCID: PMC5385549 DOI: 10.1038/srep45997] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 03/07/2017] [Indexed: 11/09/2022] Open
Abstract
The structural, chemical, and magnetic properties of magnetite nanoparticles are compared. Aberration corrected scanning transmission electron microscopy reveals the prevalence of antiphase boundaries in nanoparticles that have significantly reduced magnetization, relative to the bulk. Atomistic magnetic modelling of nanoparticles with and without these defects reveals the origin of the reduced moment. Strong antiferromagnetic interactions across antiphase boundaries support multiple magnetic domains even in particles as small as 12-14 nm.
Collapse
Affiliation(s)
- Zlatko Nedelkoski
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK
| | | | - Leonardo Lari
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK
| | - Tianlong Wen
- Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, China
| | - Ryan A. Booth
- Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Samuel D. Oberdick
- Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Pedro L. Galindo
- Department of Computer Science and Engineering, Universidad de Cádiz, 11510 Puerto Real, Spain
| | | | | | - Sara Majetich
- Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Vlado K. Lazarov
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK
| |
Collapse
|
4
|
Gilks D, Nedelkoski Z, Lari L, Kuerbanjiang B, Matsuzaki K, Susaki T, Kepaptsoglou D, Ramasse Q, Evans R, McKenna K, Lazarov VK. Atomic and electronic structure of twin growth defects in magnetite. Sci Rep 2016; 6:20943. [PMID: 26876049 PMCID: PMC4753457 DOI: 10.1038/srep20943] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 01/14/2016] [Indexed: 12/04/2022] Open
Abstract
We report the existence of a stable twin defect in Fe3O4 thin films. By using aberration corrected scanning transmission electron microscopy and spectroscopy the atomic structure of the twin boundary has been determined. The boundary is confined to the (111) growth plane and it is non-stoichiometric due to a missing Fe octahedral plane. By first principles calculations we show that the local atomic structural configuration of the twin boundary does not change the nature of the superexchange interactions between the two Fe sublattices across the twin grain boundary. Besides decreasing the half-metallic band gap at the boundary the altered atomic stacking at the boundary does not change the overall ferromagnetic (FM) coupling between the grains.
Collapse
Affiliation(s)
- Daniel Gilks
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK
| | - Zlatko Nedelkoski
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK
| | - Leonardo Lari
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK
| | | | - Kosuke Matsuzaki
- Secure Materials Centre, Materials and Structures Laboratory, Tokyo Institute for Technology, 4259 Nagatsuta, Midori-ku, Yokohama-city, Kanagawa, 226-8503, Japan
| | - Tomofumi Susaki
- Secure Materials Centre, Materials and Structures Laboratory, Tokyo Institute for Technology, 4259 Nagatsuta, Midori-ku, Yokohama-city, Kanagawa, 226-8503, Japan
| | - Demie Kepaptsoglou
- SuperSTEM, STFC Daresbury Laboratories, Keckwick Lane, Warrington, WA4 4AD, UK
| | - Quentin Ramasse
- SuperSTEM, STFC Daresbury Laboratories, Keckwick Lane, Warrington, WA4 4AD, UK
| | - Richard Evans
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK
| | - Keith McKenna
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK
| | - Vlado K Lazarov
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK
| |
Collapse
|
5
|
Bernal-Villamil I, Gallego S. Electronic phase transitions in ultrathin magnetite films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:293202. [PMID: 26153727 DOI: 10.1088/0953-8984/27/29/293202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Magnetite (Fe3O4) shows singular electronic and magnetic properties, resulting from complex electron-electron and electron-phonon interactions that involve the interplay of charge, orbital and spin degrees of freedom. The Verwey transition is a manifestation of these interactions, with a puzzling connection between the low temperature charge ordered state and the dynamic charge fluctuations still present above the transition temperature. Here we explore how these rich physical phenomena are affected by thin film geometries, particularly focusing on the ultimate size limit defined by thicknesses below the minimum bulk unit cell. On one hand, we address the influence of extended defects, such as surfaces or antiphase domains, on the novel features exhibited by thin films. On the other, we try to isolate the effect of the reduced thickness on the electronic and magnetic properties. We will show that a distinct phase diagram and novel charge distributions emerge under reduced dimensions, while holding the local high magnetic moments. Altogether, thin film geometries offer unique possibilities to understand the complex interplay of short- and long-range orders in the Verwey transition. Furthermore, they arise as interesting candidates for the exploitation of the rich physics of magnetite in devices that demand nanoscale geometries, additionally offering novel functionalities based on their distinct properties with respect to the bulk form.
Collapse
Affiliation(s)
- I Bernal-Villamil
- Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid, Spain
| | | |
Collapse
|
6
|
McKenna KP, Hofer F, Gilks D, Lazarov VK, Chen C, Wang Z, Ikuhara Y. Atomic-scale structure and properties of highly stable antiphase boundary defects in Fe 3O 4.. Nat Commun 2014; 5:5740. [PMID: 25494005 PMCID: PMC4275585 DOI: 10.1038/ncomms6740] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 11/03/2014] [Indexed: 11/29/2022] Open
Abstract
The complex and intriguing properties of the ferrimagnetic half metal magnetite (Fe3O4) are of continuing fundamental interest as well as being important for practical applications in spintronics, magnetism, catalysis and medicine. There is considerable speculation concerning the role of the ubiquitous antiphase boundary (APB) defects in magnetite, however, direct information on their structure and properties has remained challenging to obtain. Here we combine predictive first principles modelling with high-resolution transmission electron microscopy to unambiguously determine the three-dimensional structure of APBs in magnetite. We demonstrate that APB defects on the {110} planes are unusually stable and induce antiferromagnetic coupling between adjacent domains providing an explanation for the magnetoresistance and reduced spin polarization often observed. We also demonstrate how the high stability of the {110} APB defects is connected to the existence of a metastable bulk phase of Fe3O4, which could be stabilized by strain in films or nanostructures. Although Fe3O4 is widely investigated for a variety of applications, the relation between some defects and its properties remains poorly understood. Here, the authors use high-resolution transmission electron microscopy and simulations to determine the atomic structure of the common antiphase boundary defects.
Collapse
Affiliation(s)
- Keith P McKenna
- 1] Department of Physics, University of York, Heslington, York YO10 5DD, UK [2] WPI-AIMR, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Florian Hofer
- Department of Physics, University of York, Heslington, York YO10 5DD, UK
| | - Daniel Gilks
- Department of Physics, University of York, Heslington, York YO10 5DD, UK
| | - Vlado K Lazarov
- Department of Physics, University of York, Heslington, York YO10 5DD, UK
| | - Chunlin Chen
- WPI-AIMR, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Zhongchang Wang
- WPI-AIMR, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Yuichi Ikuhara
- WPI-AIMR, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| |
Collapse
|