UCD School of Physics

Scoil na Fisice UCD

Publication highlights 2015-16

For the complete list of publications of School of Physics in 2015-2016 click here.

Andrew Mitchell with coworkers developed a quantum theory describing groundbreaking new experiments on nanoscale quantum dot devices. The system exhibits universal quantum critical physics due to frustrated strong electronic interactions, leading to the formation of Majorana fermions. Quantitative agreement between their theory and experiment was obtained over an unprecedented 9 orders of magnitude. This research was published in Phys. Rev. Lett. 116, 157202 (2016). A different aspect of the quantum theory of condensed matter was studied in Phys. Rev. Lett. 117, 037202 (2016) – quantum spin liquids which resist magnetic ordering due to strong quantum fluctuations. However, a more exotic topological order does develop. Despite the non-local character of the order in spin liquids, it was shown how they can still be probed locally by 'impurity' qubits, which settled a long-standing question regarding their phase diagram.

Vladimir Lobaskin in collaboration with Roland Netz (Free University Berlin) described a diffusive-convective transition in electrolyte dynamics at the nanoscale. The cooperative motion in these systems arises due to hydrodynamic coupling between the ions moving in the same direction and leads to an effective attraction between like-charged ions and faster relaxation of the ionic double layer. This work was published in Europhysics Letters 116: 58001 (2016).

Antonio Benedetto participated in a development of a method of Elastic Scattering Spectroscopy (ESS). The instrument can be used for studying dynamics of complex (bio-) systems. The combined experiment and simulation study is published in Scientific Reports (Sci. Rep. 6, 34266 (2016) http://dx.doi.org/10.1038/srep34266)

Hans-Benjamin Braun developed a theory of magnetic skyrmions, topologically non-trivial whirls, which appear in the magnetisation field inside materials like MnSi and Fe_0.5Co_0.5Si. Unlike magnetisation vortices, the skyrmions leave the ferromagnetic state intact far away from their core. The dynamic skyrmions have great potential for both new physics and direct applications in skyrmionics and NC-based microwave signal generators. The work is published in Nature Communications (Article 8193, 2015, http://dx.doi.org/10.1038/ncomms9193).

HB Braun Skyrmion

Panels (a–e) show skyrmions with skyrmion number . (a) A bubble skyrmion (b) A chiral skyrmion as favoured in B20-type materials such as MnSi. (c) A hedgehog skyrmion as favoured by interfacial DMI. (d) Dynamically stabilised magnetic skyrmion. (e) For vanishing dipolar interactions (DDI), DMI and Oe fields, and in absence of damping, the skyrmion precesses uniformly and breathing disappears.

Cathal Leahy, Ronan Murphy, and Vio Buchete in collaboration with Edina Rosta (Univ. College London) and Gerhard Hummer (MPI Biophysics, Frankfurt) published a work "Coarse Master Equations for Binding Kinetics of Amyloid Peptide Dimers" in J. Phys. Chem. Lett. (7, 2676 (2016); http://dx.doi.org/10.1021/acs.jpclett.6b00518). The simulations performed using temperature replica-exchange molecular dynamics give insights into mechanisms of formation of amyloid aggregates.