Mapping magnetic anisotropy: rational design of high-blocking temperature nanomagnets
Lead Research Organisation:
University of Glasgow
Department Name: School of Chemistry
Abstract
Magnetic materials are all around us in everyday life and we rely on devices that store data without a second thought, expecting the next gadget to be smaller and with an increased storage capacity. The materials used to store data are made using a 'top-down' approach: magnetic particles made in this way can not continue to decrease in size indefinitely, as thermally activated magnetization reversal will lead to data loss. However, using a 'bottom-up' approach, we can produce magnetic molecules, which are easy to synthesise, cheap and are monodisperse. Hence, we can envisage information storage at ultra-high Pbit / in2 densities, by using a self-assembled array of molecular bits on a surface, with each molecule just a few nanometres in size.
Although these molecules are easy to synthesise, current approaches afford little control over the structure of the molecule and hence, limited control over the resultant magnetic properties. Therefore, these potentially fascinating molecules display their interesting magnetic properties only at very low temperatures. To increase the so-called blocking temperature, we need to develop much greater level of control. The key requirement is that the molecule has a large easy-axis magnetic anisotropy associated with the spin ground state. However, the rules for controlling the anisotropy of magnetic molecules are not well understood. By synthesising families of these molecules and tuning the structure, along with detailed magnetic measurements and theoretical calculations, we will develop the magnetostructural correlations that determine the overall anisotropy. Hence, we will tune and increase the magnetic anisotropy, providing an unprecedented level of control in the production of high-blocking temperature magnetic molecules.
Although these molecules are easy to synthesise, current approaches afford little control over the structure of the molecule and hence, limited control over the resultant magnetic properties. Therefore, these potentially fascinating molecules display their interesting magnetic properties only at very low temperatures. To increase the so-called blocking temperature, we need to develop much greater level of control. The key requirement is that the molecule has a large easy-axis magnetic anisotropy associated with the spin ground state. However, the rules for controlling the anisotropy of magnetic molecules are not well understood. By synthesising families of these molecules and tuning the structure, along with detailed magnetic measurements and theoretical calculations, we will develop the magnetostructural correlations that determine the overall anisotropy. Hence, we will tune and increase the magnetic anisotropy, providing an unprecedented level of control in the production of high-blocking temperature magnetic molecules.
Planned Impact
Data storage represents a huge market force, but current magnetic materials are rapidly approaching their fundamental limit and it is imperative that new magnetic materials are developed. In order to reach even higher density, it is necessary to make smaller and smaller bits. If the bit size is to decrease further towards a few nanometres, we move into the realm of magnetic molecules, where properties can be designed by building up a molecule one magnetic atom at a time. Magnetic molecules are easy to synthesise, cheap and are monodisperse, allowing for self-assembly of an array of molecular bits on a surface. In the long term, the microelectronics / nano-fabrication industries will be the major beneficiaries of this research at all levels from multi-nationals to SMEs and spinout companies. In addition UK HEIs, students and the general public will also be beneficiaries, not to mention the UK-plc as a whole.
Industry: Micro- / nanoelectronics are everywhere and very few people do not use any electronic technologies: new molecule-based technologies offer the promise of a disruptive technology for tomorrow's society, and their study triggers new fundamental research in emerging fields. The field of molecular magnetism is strongly connected with other nanosciences. The molecular approach can be exploited in the preparation of magnetic nanostructures, like nanoparticles, wires, or layers for use in industrial (semiconductor / microelectronics / nano-fabrication) or biomedical applications. A key advantage of the molecular approach to magnetism is the potential to remove non-uniformity and variability in devices, as one magnetic molecule will be exactly the same as the next. Also, this monodispersity will permit self-assembly of an array of molecular bits on a surface to overcome the challenges of patterning a magnetic film into nm-scale islands. These molecular systems could be of interest to SMEs and spin-outs in the development of niche applications such as magnetic refrigeration, magneto-optical data storage, novel MRI contrast agents and molecular spintronic devices or as components of 3rd party applications such as magneto-optical switches or sensors. The race towards the molecular limit is gathering pace and this research will produce a highly skilled scientist and add to the future economic competitiveness of the UK in a knowledge-based economy.
Industry: Micro- / nanoelectronics are everywhere and very few people do not use any electronic technologies: new molecule-based technologies offer the promise of a disruptive technology for tomorrow's society, and their study triggers new fundamental research in emerging fields. The field of molecular magnetism is strongly connected with other nanosciences. The molecular approach can be exploited in the preparation of magnetic nanostructures, like nanoparticles, wires, or layers for use in industrial (semiconductor / microelectronics / nano-fabrication) or biomedical applications. A key advantage of the molecular approach to magnetism is the potential to remove non-uniformity and variability in devices, as one magnetic molecule will be exactly the same as the next. Also, this monodispersity will permit self-assembly of an array of molecular bits on a surface to overcome the challenges of patterning a magnetic film into nm-scale islands. These molecular systems could be of interest to SMEs and spin-outs in the development of niche applications such as magnetic refrigeration, magneto-optical data storage, novel MRI contrast agents and molecular spintronic devices or as components of 3rd party applications such as magneto-optical switches or sensors. The race towards the molecular limit is gathering pace and this research will produce a highly skilled scientist and add to the future economic competitiveness of the UK in a knowledge-based economy.
People |
ORCID iD |
Mark Murrie (Principal Investigator) |
Publications
Binns J
(2016)
A non-topological mechanism for negative linear compressibility.
in Chemical communications (Cambridge, England)
Collet A
(2018)
Slow magnetic relaxation in a {CoIICo} complex containing a high magnetic anisotropy trigonal bipyramidal CoII centre.
in Dalton transactions (Cambridge, England : 2003)
Craig GA
(2018)
Probing the origin of the giant magnetic anisotropy in trigonal bipyramidal Ni(ii) under high pressure.
in Chemical science
Hay M
(2019)
Investigation of the magnetic anisotropy in a series of trigonal bipyramidal Mn( ii ) complexes
in Dalton Transactions
Hay MA
(2020)
A large axial magnetic anisotropy in trigonal bipyramidal Fe(ii).
in Chemical communications (Cambridge, England)
Marriott KER
(2015)
Pushing the limits of magnetic anisotropy in trigonal bipyramidal Ni(ii).
in Chemical science
Description | The miniaturization of data storage devices has led to a drastic reduction in the size of the basic unit of information, or bit. Understanding and controlling the magnetic anisotropy of these materials is vital for the future of computers, cell phones and other electronics. A single atom has the potential to be the smallest unit of magnetic memory storage. By designing molecules containing just one or a handful of magnetic atoms, we can engineer the magnetic anisotropy. This property locks the north/south poles of the magnetic atom so that they point in only one of two directions: the magnetic anisotropy has to be strong in order to prevent reorientation of the magnet and, therefore, a loss of its stored information. We have designed new nanomagnets based on just one transition metal ion in a carefully controlled environment, that display the largest ever reported magnetic anisotropy. The project is ongoing, but in the long term we will be able to say what the individual building blocks for improved single-molecule magnets look like and hence, show how blocking temperatures can be increased by design. |
Exploitation Route | We have shown how the magnetic anisotropy of new nanomagnets based on just one transition metal ion can be maximised by chemical design. Such design rules will have wide impact in the long term. |
Sectors | Chemicals,Electronics |
URL | https://nationalmaglab.org/user-facilities/emr/emr-publications/highlights-emr/magnetic-anisotropy |
Description | This grant formed the basis for training a PDRA in the most up-to-date scientific methodologies and techniques, both in the home-lab and at central facilities (in particular at the National High Magnetic Field Laboratory in Florida). This involved not only intricate experimental manipulations, but also the analysis of structural and magnetic data sets and computational modelling of data. The combination of training provided in advanced experimental techniques, the ability to analyse data and presentation of the results in a concise manner are highly transferable skills. The PDRA hired on the grant drafted the publications reporting their data and presented their work at conferences. In particular the work published in Chemical Science (Chem. Sci., 2015, 6, 6823; https://doi.org/10.1039/C5SC02854J ) has had far reaching impact within academia, receiving over 100 citations. |
Impact Types | Economic |
Description | University of Glasgow PhD studentship |
Amount | £65,000 (GBP) |
Organisation | University of Glasgow |
Sector | Academic/University |
Country | United Kingdom |
Start | 10/2015 |
End | 04/2019 |
Title | Pushing the limits of magnetic anisotropy in trigonal bipyramidal Ni(II). |
Description | |
Type Of Material | Database/Collection of data |
Year Produced | 2015 |
Provided To Others? | Yes |
Description | Computational studies |
Organisation | Indian Institute of Technology Bombay |
Country | India |
Sector | Academic/University |
PI Contribution | We synthesized and characterized the samples, in particular using single-crystal X-ray diffraction. |
Collaborator Contribution | They used the single-crystal X-ray diffraction data to calculate key magnetic parameters such as the magnetic anisotropy. |
Impact | The collaboration brings computational chemistry (DFT and ab initio) expertise. Output = DOI: 10.1039/C7SC04460G. |
Start Year | 2016 |
Description | HFEPR |
Organisation | US National High Magnetic Field Laboratory |
Country | United States |
Sector | Public |
PI Contribution | Synthesis of samples for high-field high-frequency EPR |
Collaborator Contribution | Measurement of samples for high-field high-frequency EPR and data interpretation |
Impact | DOI: 10.1039/B807447J Multidisciplinary: Chemistry & Physics |
Start Year | 2006 |
Description | MicroSQUID |
Organisation | National Center for Scientific Research (Centre National de la Recherche Scientifique CNRS) |
Department | Grenoble High Magnetic Field Laboratory |
Country | France |
Sector | Public |
PI Contribution | Synthesis of samples (single crystals) for ultra-low temperature magnetic measurements |
Collaborator Contribution | Measurement of magnetic properties of samples (single crystals) at ultra-low temperatures |
Impact | DOI: 10.1021/ic500885r Multidisciplinary: chemistry & physics |