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A novel metamagnetic compound: bulk metallo-fullerenes

PGR-P-760

Key facts

Type of research degree
PhD
Application deadline
Wednesday 1 July 2020
Project start date
Thursday 1 October 2020
Country eligibility
UK and EU
Funding
Competition funded
Source of funding
Research council
Additional supervisors
Dr. Oscar Cespedes; Prof. Andrew Mullis; Dr. Aidan Westwood
Schools
School of Chemical and Process Engineering, School of Physics and Astronomy
<h2 class="heading hide-accessible">Summary</h2>

Power generation and conversion are amongst the main uses of magnetic materials, from wind turbines to electrical vehicles. These applications make use of rare earths (REs) such as samarium or neodymium to harden the magnetic hysteresis of transition metals. Adding REs increases vastly the amount of energy that can be stored in a magnet, and therefore its efficiency. World demand for REs is estimated at 150 ktons/year, or $4.5 billion and it has increased monotonically for the last 30 years &ndash;about 20% for use in magnets. REs are dangerous to process, highly damaging to the environment and difficult to recycle &ndash;less than 1% are reused. Furthermore, the supply chain is hostage to political uncertainties. At the School of Physics and Astronomy in Leeds, we have pioneered research in the use of carbon-based molecules to enhance the quantum interactions behind magnetism, resulting e.g. in an induced magnetisation in normal metals. Recently, we measured a molecule-metal bilayer whose low-T coercivity of 1.6 T and energy product of 350 kJ/m3 rivals or even exceeds those of RE magnets. Since these results are obtained using a non-magnetic molecule, C60, such large coercivities cannot be explained by conventional models. Instead, we have proposed a new form of interaction, dubbed &pi;-anisotropy, based on the spin-dependent &pi;-d hybridisation at metallo-molecular interfaces. This effect is currently limited to low temperatures because of C60 rotation, but this studentship will research composites in bulk phase that could exhibit this behaviour at higher temperatures. Prof. Mullis and Dr. Westwood at the School of Chemical and Process Engineering will contribute their expertise and facilities in metallurgy, solidification and advanced carbon nanomaterials composites. Dr Teobaldi (Group Leader, Theoretical and Computational Physics; SCD-STFC) will contribute with state-of-the-art DFT simulations of these systems. The student will become an expert on magnetometry, microscopy, non-equilibrium processing and thin film growth. Work will start by working with low reactivity and low-temperature melt metals (e.g. indium)-C60 (months 1-3), then moving to Cu-C60 (potential emergent magnetism) and then to Co and Fe/C60 (m. 12-24) before exploring C70 in the most promising combinations. We note that C60 and C70 are resilient and does not break up to temperatures of several thousand degrees. The goal is to increase by a factor 10 the room temperature energy product of nanocarbon-Fe and/or Co hybrids. This would result in lighter, eco-friendly and powerful magnets fabricated from abundant elements.

<h2 class="heading hide-accessible">Full description</h2>

<p>Power generation and conversion are amongst the main uses of magnetic materials, from wind turbines to electrical vehicles. These applications make use of rare earths (REs) such as samarium or neodymium to harden the magnetic hysteresis of transition metals. Adding REs increases vastly the amount of energy that can be stored in a magnet, and therefore its efficiency. World demand for REs is estimated at <strong><em>150 ktons/year, or $4.5 billion</em> </strong>and it has increased monotonically for the last 30 years &ndash;about 20% for use in magnets. REs are dangerous to process, highly damaging to the environment and difficult to recycle &ndash;less than 1% are reused. Furthermore, the supply chain is hostage to political uncertainties. Reducing our dependence on these materials would have huge economical, societal and political repercussions.</p> <p>We have <strong><em>pioneered research</em></strong> in the use of carbon-based molecules to enhance the quantum interactions behind magnetism, resulting e.g. in an induced magnetisation in normal metals. Recently, we measured a molecule-metal bilayer whose low-T <strong><em>coercivity of 1.6 T and energy product of 350 kJ/m<span class="superscript_text">3</span></em></strong> <strong><em>rivals or even exceeds those of RE magnets.</em></strong> Since these results are obtained using a non-magnetic molecule, C, such large coercivities cannot be explained by conventional models. Instead, we have proposed a <strong><em>new form of interaction</em></strong>, dubbed &pi;-anisotropy, based on the spin-dependent &pi;-d hybridisation at metallo-molecular interfaces. This effect is currently limited to low temperatures because of C rotation, but this studentship will research composites in bulk phase that could exhibit this behaviour at higher temperatures.</p> <p>Prof. Mullis and Dr. Westwood contribute leading expertise and facilities in metallurgy, solidification and advanced carbon nanomaterials composites, complementing Drs. Cespedes &amp; Moorsom background in magnetic and molecular thin films at Physics. Dr Teobaldi (; SCD-STFC) has agreed to<strong><em> provide state-of-the-art DFT simulations</em></strong> of the magnetic and structural properties of these systems. The &shy;&shy;student will become an expert on world-class magnetometry, microscopy, non-equilibrium processing and thin film growth facilities at Leeds &ndash;key in this work. Work will start by working with low reactivity and low-T melt metals (e.g. indium)-C (months 1-3), then moving to Cu-C (potential emergent magnetism [3]; m. 4-11) and then to Co and Fe/C (m. 12-24) before exploring C in the most promising combinations (m. 25-32) and write up (m. 33-36). We note that C and C are resilient and does not break up to temperatures of several thousand degrees. The goal is to <strong><em>increase by a factor 10 the room temperature energy product</em></strong> of nanocarbon-Fe and/or Co hybrids. This would result in lighter, eco-friendly and powerful magnets fabricated from abundant elements.</p> <p><strong>[1]</strong> M. Humphries, Rare earth elements &ndash; the global supply chain. Report for US Congress, 2013 (<a href="https://fas.org/sgp/crs/natsec/R41347.pdf">https://fas.org/sgp/crs/natsec/R41347.pdf</a><cite>); </cite><strong>[2]</strong> L. Hornby and H. Sanderson, Rare earths: Beijing threatens a new front in the trade war, Financial Times, June 2019.<cite><strong> [3]</strong></cite><cite> F. Al Ma&rsquo;Mari et al., Nature 524, 69 (2015); PNAS 114, 5583 (2017); </cite><strong>[4]</strong> T. Moorsom et al., Phys. Rev. B 101, 060408(R) (2020), and Phys. Rev. B 90, 125311 (2014).</p>

<h2 class="heading">How to apply</h2>

<p>Formal applications for research degree study should be made online through the&nbsp;<a href="http://www.leeds.ac.uk/rsa/prospective_students/apply/I_want_to_apply.html">University&#39;s website</a>. Please state clearly in the research information section&nbsp;that the research degree you wish to be considered for is &lsquo;A novel metamagnetic compound: bulk metallo-fullerenes&rsquo; as well as&nbsp;<a href="https://eps.leeds.ac.uk/physics/staff/4101/dr-oscar-cespedes">Dr Oscar Cespedes</a> as your proposed supervisor.</p> <p>If English is not your first language, you must provide evidence that you meet the University&#39;s minimum English language requirements (below).</p> <p><em>We welcome applications from all suitably-qualified candidates, but UK black and minority ethnic (BME) researchers are currently under-represented in our Postgraduate Research community, and we would therefore particularly encourage applications from UK BME candidates. All scholarships will be awarded on the basis of merit.</em></p>

<h2 class="heading heading--sm">Entry requirements</h2>

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

<h2 class="heading heading--sm">English language requirements</h2>

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.

<h2 class="heading">Funding on offer</h2>

<p>A highly competitive EPSRC Studentship Award offering Academic Fee at Home/EU Fee rate, plus Maintenance of &pound;15,285 per year for 3.5 years.</p> <p description="" full="">The Award can be used to fund projects that would be co-supervised across (at least) two schools within the Faculty of Engineering and Physical Sciences.</p> <p><strong>Note to EU Candidates:</strong>&nbsp;&nbsp;To be eligible for the full award of fees and maintenance, you must&nbsp;have residency in the UK for 3 or more years prior to your start date.&nbsp;If you do not have 3 years residency in the UK, you may be eligible for a&nbsp;<strong>Fee Only</strong>&nbsp;award.</p> <p>Please note that International applicants are not eligible to apply for this funding.</p>

<h2 class="heading">Contact details</h2>

<p>For further information regarding your application, please contact Doctoral College Admissions:<br /> e:&nbsp;<a href="mailto:phd@engineering.leeds.ac.uk">phd@engineering.leeds.ac.uk</a>&nbsp;or t: +44 (0)113 343 5057</p> <p>For further information regarding the project, please contact Dr Oscar Cespedes by email:&nbsp;&nbsp;<a href="mailto:O.Cespedes@leeds.ac.uk">O.Cespedes@leeds.ac.uk</a>&nbsp;</p>


<h3 class="heading heading--sm">Linked funding opportunities</h3>
<h3 class="heading heading--sm">Linked research areas</h3>