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Opportunities

Marie Curie studentships available now!

Two PhD positions at TCD in the new MaMi (Magnetics and Microhydrodynamics) Innovative Training Network (2018 - 2022) have to be filled soon!

We need talented and curious candidates to join a unique interdisciplinary group of academic and industrial researchers in Dublin, Strasbourg, Paris, Gottingen, Bilbao, Riga and Lubljana who aim to combine magnetism and bio-inspired local flow with liquid-in-liquid confinement to create novel concepts and technological solutions which will revolutionise microfluidics.

The two projects based in Dublin are 'Structure of concentrated ionic solutions & their response to magnetic fields' and 'Correlation of surface wettability to material electronic properties'. All PhD positions will include sencondements to partner labs and some industrial training. Excellent candidates should send a CV and letter of motivation to Prof. Michael Coey at jcoey@tcd.ie, preferably 4th of June.

Project 1

Diffusion in liquids is usually treated in terms of uncorrelated random thermal motion of dilute dissolved ions, directed by a concentration gradient. The concentrated limit is complex, and the distinction between diffusion and advection becomes blurred when the motions of ions are highly correlated. It seems that ions in concentrated solutions move in highly-correlated groups of about 105 [1]. The response of concentrated aqueous solutions to a magnetic field gradient will provide important insight into these correlations; a drop of paramagnetic solution in water can be easily manipulated by a magnet, although the magnetic field gradient forces on single isolated ions are orders of magnitude less than the entropic force driving their diffusion. The dynamic structure and the resulting magnetophoresis will be investigated by magnetic studies of 3d and 4f ions, coupled with synchrotron studies of dynamic structural correlation, and small-angle neutron scattering (collaboration with the LLB in Paris), complemented by molecular dynamics simulations in Gottingen. Results will be i) a proof of concept of magnetic separation of rare earth ions in solution using magnetic field gradients and ii) improved design of magnetic antitubes [2] where a filament of pure water is confined by a surrounding paramagnetic solution in a quadrupolar magnetic field. The project includes training in patent writing and IP protection in Strasbourg.

Project 2

The contact angles of water on boron nitride and graphite are strikingly different [3]. The former is moderately hydrophilic whereas the latter is hydrophobic. A consequence is the remarkable ability of water to flow with little pressure gradient through individual carbon nanotubes, in contradiction to the no-slip boundary condition that applies for structurally-similar boron nitride. This points to a link between hydrodynamic flow and the electronic structure of the confining material. This project sets out to understand the origin of the effect and to apply it in the context of 'microfluidics without walls' taking advantage of the experience of University of Bilbao in microfluidics, and the parallel efforts in frictionless microfluidic channels in Strasbourg. This project includes an industrial seconment with ELVESYS in Strasbourg.

References

[1] O.Y. Gorobets, Y.I. Gorobets and V.P. Rospotniuk, J. Appl. Phys., 118 (2015), 73902.
[2] J.M.D. Coey et al., Proc. Natl. Acad. Sci., 106 (2009), 8811-17.
[3] E. Secchi et al., Nature, 537 (2016), 210-13.


THz Gap

Open positions in the ‘Magnetism and Spin Electronics Group’ at Trinity College Dublin

The group has secured contracts for two new projects and are currently looking to take on a post-doc and two PhD students.

‘TRANSPIRE’, funded by the European Commission through the FET-OPEN scheme, will run for four years. The project aims to develop new chip-based spin-torque nano-oscillators that will advance electronics into the previously inaccessible terahertz frequency domain, thereby sustaining the big data revolution for another 25 years [1]. The key here is the ability of thin-film trilayer stacks to exhibit an oscillating magnetotesistance when a spin-polarized electric current transfers angular momentum from one magnetically-ordered electrode to the other, thereby exciting Larmor precession. The frequency of oscillation is determined by the effective anisotropy field in the Kittel equation for magnetic resonance. The discovery [2] of the Group in 2014 of the first experimental zero-moment half metal (Mn2Ru0.5Ga) ‘MrG’ where the anisotropy field diverges at compensation allows this effective field to be tuned continuously close to compensation to attain frequencies ranging from hundreds of GHz up to a few THz. The project is a collaboration between TCD and two German groups (A. Deac and M. Gensch of the Helmholtz Zentrum Dresden), a theory group in Norway (A. Brataas, NTNU, Trondheim) and a Swiss industrial partner (Swissto12, Lausanne).

The second project associates research centres in Ireland and the USA; it is jointly funded by Science Foundation Ireland (SFI), The Department of Learning – Northern Ireland (DLNI) and the US National Science Foundation (NSF). The project targets energy consumption during switching of magnetic elements for data storage. A promising way to combine high switching speeds with low energy consumption relies on voltage control of magnetic anisotropy. The set of manganese-based ferrimagnets (Mn3-xGa, Mn3Ge, Mn2FeGa) previously developed by the Group have many of the necessary requirements, including a high anisotropy constant coupled with a low density of states at the Fermi level and crucially a high degree of spin polarisation necessary to achieve high magnetoresistance. Partners here are UC Berkley (Ramesh) UCLA (Kang Wang) and QUB (Solveig Felton, Marty Gregg).

Thin film stacks will grown by sputtering or pulsed laser deposition in a new 3M€ multi–chamber deposition tool (delivery expected end 2017). Prior experience with thin film sample deposition is therefore expected. The post-doctoral researcher should have experience of magnetic thin film devices, fast magneto-optics or ferromagnetic resonance. The films and devices will be extensively characterized in-house, and in large-scale European facilities. The magnetisation dynamics will be probed by cavity and strip-line FMR and by time-resolved MOKE. Prior experience with fast optics would be an advantage.

One PhD student will work closely with the postdoc, the other will have a focus on materials growth and characterisation. A successful candidate will have a good a bachelor’s degree in experimental or theoretical physics or materials science.

The postdoc position is initially for 2 years, at 40 – 48k€, whereas the PhD position is funded for the 4 years duration of the degree at 16 – 18k€ plus fees.

[1] D. Betto, et al., ‘The zero–moment half metal: How could it change spin electronics?’, AIP Adv., vol. 6, no. 5, pp. 055601, 2016. [2] H. Kurt, et al., ‘Cubic Mn2Ga Thin Films: Crossing the Spin Gap with Ruthenium’, Phys. Rev. Lett., vol. 112, no. 2, pp. 027201, 2014.

For further information please contact stamenop@tcd.ie, rodek@tcd.ie or jcoey@tcd.ie