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Viewing upcoming talks containing the keyword: 3
Cond Mat Seminars
Speaker: Alexander Balatsky (NORDITA, Stockholm)
Dynamics of quantum matter and time domain orders is an active and rapidly evolving field. I will discuss the status of the search for dynamic superconducting order known as odd frequency superconductivity (OFSC) and the relation between OFSC and time crystals. I also will review proposed experimental platforms to realize this superconducting state. Specifically, I will 1) illustrate the ubiquity of OFSC in conventional superconductors and conventional Josephson effect, 2) I will also present views on the OFSC as an example of the dynamic order and how it can be realized in the driven SC systems and 3) highlight the connection of the OFSC to the topological excitations and the use of interacting Majorana fermions as a state where of the OFSC is a ground state. 
 Jacob Linder, Alexander V. Balatsky, Odd-frequency superconductivity, arXiv:1709.03986
On: July 9, 2019 From: 11h00 To: 12h00View talk
Cond Mat Seminars
Speaker: Alexander Balatsky (NORDITA, Stockholm)
It is well established that multiple entangled orders emerge in quantum materials at criticality: e.g. superconducting states develop in the vicinity of magnetic phases. I will make the case that similar phenomena occur in quantum paraelectrics. Recent observations of strain effects and O18 isotope substitution in doped STO support the view of the key role critical ferroelectric fluctuations play in producing superconductivity [1,2,3,4]. Looking beyond superconductivity, I will illustrate how quantum ferroelectric fluctuations can induce magnetic fluctuations due to recently proposed phenomenon of dynamic multiferroicity [5,6]. *
*This work supported by the ERC Synergy HERO, VILLUM FONDEN via the Centre of Excellence for Dirac Materials (Grant No. 11744) and KAW.
 JM Edge, et.al., Quantum Critical Origin of the Superconducting Dome in SrTiO3, PHYSICAL REVIEW LETTERS 117 (21) (2015).  CW Rischau, et.al., A ferroelectric quantum phase transition inside the superconducting dome of Sr1−xCaxTiO3−δ, Nature Physics 13 (7), 643 (2017).  Dunnett, K., Narayan, A., Spaldin, N. A. & Balatsky, A. V. Strain and ferroelectric soft-mode induced superconductivity in strontium titanate. Phys. Rev. B 97, 144506 (2018).  A Stucky, et.al., Isotope effect in superconducting n-doped SrTiO3, Scientific Reports, volume 6, Article number: 37582 (2016).  Juraschek, D. M., Fechner, M., Balatsky, A. V & Spaldin, N. A. Dynamical multiferroicity. Phys.Rev. Mater. 1, 14401 (2017).  Dunnett K., et.al, Dynamic multiferroicity of a ferroelectric quantum critical point, arXiv:1808.05509, PRL 122 (5), 057208, (2019).
On: July 10, 2019 From: 11h00 To: 12h00View talk
Speaker: Andrew Blaikie ()
There are estimated to be 285 million visually and 360 million hearing impaired people in the world with the majority of cases considered preventable or treatable if diagnosed promptly. Ophthalmoscopes and otoscopes are typically designed for markets of wealthy countries and are complex, heavy and expensive with their basic design remaining relatively unchanged for over 100 years. Unfortunately only very few practitioners in low and middle-income countries (LMICs) have these essential tools. If they do own devices they are typically ‘hand-me-downs’ from well-minded donors but often not functional being dependent upon hard to find and expensive consumables such as bulbs and batteries. Sadly the vast majority of cases of vision and hearing impairment are however found in LMICs where access to diagnostic tools is least. The Lancet Commission’s report on Technologies for Global Health has consequently recommended greater focus on ‘frugal technologies’ designed for the needs of LMICs rather than the markets of wealthy countries. We describe the inspiration, development and potential of the Arclight a novel low cost ‘frugal’ diagnostic tool for prevention of vision and hearing impairment.
On: July 25, 2019 From: 13h00 To: 14h00View talk
Speaker: Dr Amit Kumar (Weizmann Institute of Science)
Pincer Catalysts for Energy & Environment Dr. Amit Kumar, Weizmann Institute of Science, Israel Catalysis plays a major role in the production of food, pharmaceuticals and energy. We have been working in the area of green homogeneous catalysis using pincer complexes of transition -metals. We have developed several interesting methods that are environmentally -benign and sustainable for the production of industrially useful chemicals f rom the cheap and inexpensive starting materials using pincer complexes of earth -abundant metals such as manganese. These metho ds are based on hydrogenation and dehydrogenation reactions which makes the overa ll process highly atom -economic and sustainable . Some of these catalytic reactions will be discussed in the lecture , such as (a) the direct synthesis of amides by the dehydrogenative coupling of amines with either alcohols or esters 1 (b) direct hydrogenation of organic carbonates , carbamates and urea de rivatives to methanol as an alternative route for the conversion of low -pressure CO 2 to methanol. 2 Additionally, application of ruthenium pincer catalysts for the discovery of fundamentally new and reversible hydrogen storage systems 3 as well as for the hydrogenative depolymerization of plastic waste will also be discussed.
1. (a) A. Kumar, N. A. E. Jalapa, G. Leitus, Y. Diskin Posner and D. Milstein, Angew. Chem. Int. Ed. , 2017 , 56 , 14992. (b) N. A. E. Jalapa, A. Kumar, G. Leitus, Y. Diskin Posner and D . Milstein, J. Am. Chem. Soc. , 2017 ,139 , 11722 . 2. (a) A. Kumar, T. Janes, N. A. E. Jalapa, D. Milstein, Angew. Chem. Int. Ed. , 2018 , 57, 12076. (b) U. K. Das, A. Kumar, Y. Ben -David, M. Iron, D. Milstein, J. Am. Chem. Soc. (manuscript under minor revision ). 3. A. Kumar, T. Janes, N. A. E. Jalapa, D. Milstein, J. Am. Chem. Soc., 2018 , 140 , 7453. Download PDF
On: August 20, 2019 From: 14h00 To: 15h00View talk
Speaker: Prof Michel Gravel (Saskatchewan)
Organocatalysis Using N-Heterocyclic Carbene s Michel Gravel University of Saskatchewan N-Heterocyclic c arbenes (NHCs) are well known for their ability to catalytically generate nucleophilic acyl anion equivalents from ald ehydes. This catalytic manifold is best exemplified by the benzoin and Stetter reactions generating α-hydroxyketones and 1,4 -dicarbonyl products, respectively. However, some of the most synthetically useful substrate combinations are not currently amenable to reactions in high chemo - or enanti oselectivity. For instance, the use of two distinct aldehydes in the cross -benzoin reaction or of simple unsaturated ketones in the intermolecular Stetter reaction do not gen erally provide products in high yield and/or enantiomeric ratio. We have rec ently made some headway in addressing both of these challenges through the use of triazolium , oxazolium, and bis(dialkylamino)cyclopropenium salts. Our progr ess in improving the scope as well as the chemo - and stereoselectivity of these classical reaction s will be presented. Download PDF
On: August 29, 2019 From: 14h00 To: 15h00View talk
Cond Mat Seminars
Speaker: Allan MacDonald (UT Austin)
Moiré patterns are ubiquitous in layered van der Waals materials. Moiré pattern devices can now be fabricated with considerable control by combining mechanical exfoliation of van der Waals layers with tear and stack techniques. I will explain why the electronic and optical properties of two-dimensional semiconductors and semimetals are strongly altered in long-period moiré superlattices, focusing in particular on the remarkable example of twisted bilayer graphene. When twisted to a magic  relative orientation angle near 1 degree the moiré superlattice minibands of bilayer graphene become extremely narrow and electronic correlations become strong. Experimental studies  of magic-angle twisted bilayer graphene (MATBG) have demonstrated that the electronic ground state can be a superconductor, a metal, or an insulator, depending on the filling of the magic angle flat bands. Insulating states occur close to most integer values of the number of electrons per moiré superlattice period, whereas superconducting states are common at fractional moiré band filling factors. In some cases, the insulating states are purely orbital ferromagnets that exhibit a quantum anomalous Hall effect. I will discuss progress that has been made toward understanding these remarkable properties  Moire bands in twisted double-layer graphene, R. Bistritzer and A.H. MacDonald, PNAS 108, 12233 (2011) Magic-angle graphene superlattices: a new platform for unconventional superconductivity, Y. Cao et al. Nature (2018).
On: September 18, 2019 From: 12h00 To: 13h00View talk