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Viewing upcoming talks containing the keyword: 3
Influencing the Properties of Lanthanide Single-Molecule Magnets with the Devilâ€™s Elements (Video Conference from Edinburgh)
Speaker: Richard Layfield (Manchester)
Single-Molecule Magnets (SMMs) are a type of molecular nanomagnet characterized by the ability to
display magnetic hysteresis that is molecular in origin, and by an effective energy barrier to reversal of the
magnetization. In addition to the fundamental interest in SMMs, the electron-transport properties of these materials
have stimulated considerable interest by virtue of their applications as components in molecular spintronic devices.
The overwhelming majority of SMMs contain ligands based on 2p elements, with N- and O-donor
ligands being particularly prevalent, but with organometallic ligands now growing in popularity. An
alternative strategy with hugely under-exploited potential for influencing the properties of SMMs is to
use ligands with heavier p-block elements as the donor atoms. Indeed, molecular magnets containing,
for example, heavier pnictogen donor ligands are extremely rare. Heavier p-block elements offer more
diffuse valence orbitals than their lighter congeners, which introduces possibilities for studying the
impact of small but potentially significant increases in covalent contributions to the predominantly
ionic lanthanide-ligand bonds.
In this lecture, the dynamic magnetic properties of a series of dysprosium ring systems with various
types of phosphorus- and arsenic-donor ligand (Figure 1) will be described. Our experimental studies
are supported by ab initio calculations, which have enabled us to construct a simple model for the
magnetic anisotropy and magnetization relaxation mechanisms in our SMMs. The theoretical model
also provides insight into how SMMs with larger anisotropy barriers may be designed, and selected
new systems with antimony- and selenium-based ligands will also be presented.
During the course of our work on molecular magnets we have also done some unusual catalysis by
mistake; twice. Selected results will be presented.
Acknowledgements: Financial support from the ERC, the EPSRC, EU MSC Actions, and the Royal
Society is gratefully acknowledged.
Selected references:  D. N. Woodruff, R. E. P. Winpenny, R. A. Layfield, Chem. Rev. 2013, 113, 5110.  R. A.
Layfield, Organometallics 2014, 33, 1084.  T. Pugh, A. Kerridge, R. A. Layfield, Angew. Chem. Int. Ed. 2015, 54, 4255.
 T. Pugh. L. Ungur, F. Tuna, E. J. L. McInnes, D. Collison, L. F. Chibotaru, R. A. Layfield Nat. Commun. 2015, 6, 7492.
 T. Pugh, V. Vieru, L. F. Chibotaru R. A. Layfield, manuscript submitted.
On: October 21, 2015 From: 15h30 To: 16h30View talk
Physics and Astronomy Colloquia
Speaker: Professor Ineke De Moortal (School of Mathematics and Statistics, University of St Andrews)
In this talk, I will give an overview of recently observed transverse, propagating velocity perturbations observed in coronal loops. These ubiquitous perturbations are observed to undergo strong damping as they propagate. Using both numerical and analytical modelling, we demonstrate that these can be understood in terms of coupling of different wave modes in the inhomogeneous boundaries of the loops: we perform 3D numerical simulations of footpoint-driven transverse waves propagating in a coronal plasma with a cylindrical density structure. Mode coupling in the inhomogeneous boundary layers of the loops leads to the coupling of the transversal (kink) mode to the azimuthal (Alfvén) mode, observed as the decay of the transverse kink oscillations. Both the numerical and analytical results show that the initial damping is Gaussian in nature, before tending to linear exponential damping at large heights. In addition, recent analysis of CoMP (Coronal Multi-channel Polarimeter) Doppler shift observations of a large, off-limb, trans-equatorial loops system show that Fourier power at the apex appears to be higher in the high-frequency part of the spectrum than expected from theoretical models. We suggest that this excess high-frequency FFT power could be tentative evidence for the onset of a cascade of the low-to-mid frequency waves into (Alfv enic) turbulence.
On: October 23, 2015 From: 10h00 To: 11h00View talk
TALK CANCELLED Shedding Light on Sulfur-Nitrogen Radical Chemistry: From Crystal Engineering to Fluorescent Radicals
Speaker: Jeremy Rawson (University of Windsor)
The family of dithiadiazolyl radicals (1) have been implemented as conducting and magnetic materials , as paramagnetic ligands in coordination chemistry  and for the development of photo-conducting materials . In these systems fine-tuning the R-group has permitted the physical properties of the radical to be modulated. More recently we have been interested to incorporate R-groups which bring their own functionality and describe the synthesis and characterisation of a series of fluorescent radicals and their stabilisation as efficient blue-emitting polymer composite films .
 J.M. Rawson, A. Alberola and A.L. Whalley, J.Mat.Chem., 2006, 16, 2560.
 K.E. Preuss, Dalton Trans., 2007, 2357.
 A. Iwasaki, L. Hu, R. Suizu, K. Nomura, H. Yoshikawa, K. Awaga, Y. Noda, K. Kawai, Y. Ouchi, K. Seki, H. Ito, Angew. Chem. Int. Ed., Engl., 2009, 48, 4022.
 Y. Beldjoudi, M. Nascimento, I. Osorio-Roman and J.M. Rawson, manuscript in preparation.
On: October 28, 2015 From: 15h30 To: 16h30View talk
Physics and Astronomy Colloquia
Speaker: Prof Stephanie Wehner (QUTech, Delft)
The laws of thermodynamics as we know them have originally been conceived to study the properties of large machines such as steam engines. Over time, statistics helped us justify these laws, where the law of large numbers allowed us to make statements about machines that indeed consist of a large number of particles. When machines become extremely small, however, not only are we unable to use such statistical methods, but quantum mechanical effects become relevant. What are the laws of thermodynamics in such regimes?
We start by establishing a second law that is valid for even the smallest quantum machines. We will then proceed to study the maximum efficiency of a heat engine, known as the Carnot efficiency. For large machines, this efficiency famously only depends on the temperatures on the heat baths we use . In contrast, we will see that at the nano scale, Carnot's law needs to be revised in the sense that more information about the bath other than its temperature is required to decide whether maximum efficiency can be achieved. In particular, we derive new fundamental limitations of the efficiency of heat engines at the nano and quantumscale that show that the Carnot efficiency can only be achieved under special circumstances, and we derive a new maximum efficiency for others. We conclude by discussing some of the many open challenges in quantum thermodynamics.
On: October 30, 2015 From: 10h00 To: 11h00View talk
Cond Mat Seminars
Speaker: Kasper Grove-Rasmussen (Niels Bohr Institute, Copenhagen)
I will present a review of our current understanding of the quantum states in a carbon nanotube quantum dot deduced from low temperature transport measurements in parallel and perpendicular magnetic fields. The observed energy spectrum is shown to be ordered in shells of two doublets consistent with a single-particle four-state model including spin-orbit interaction, valley mixing and an orbital g-factor . Furthermore, for certain shells, the two doublets are observed to be differently coupled to the leads, resulting in gate-dependent level renormalization. By comparison to the shell model this is shown to be a consequence of intra-shell valley mixing in the nanotube. Moreover, a parallel magnetic field is shown to reduce this mixing and thus suppress the effects of tunnel-renormalization .
Finally, I will give an idea of our on-going effort on nanotube Cooper pair splitters. We are particular interested in utilizing our understanding of the level structure and spin-orbit coupling presented above to fabricate devices, which are predicted to be ideal for testing the spin entanglement of split Cooper pairs . Experimental results on a bent nanotube Cooper pair splitters will be compared to the requirement for ultimately demonstrating entanglement.
 T. Sand Jespersen, K. Grove-Rasmussen, J. Paaske, K. Muraki, T. Fujisawa, J. Nygård, and K. Flensberg, Nat. Phys. 7, 348 (2011).
 K. Grove-Rasmussen, S. Grap, J. Paaske, K. Flensberg, S. Andergassen, V. Meden, H. I. Jørgensen, K. Muraki, and T. Fujisawa, Phys. Rev. Lett. 108, 176802 (2012).
 B. Braunecker, P. Burset, and A. Levy Yeyati, Phys Rev. Lett. 109, 166403 (2012)
On: November 4, 2015 From: 13h00 To: 14h00View talk