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- ItemChiral Spin Liquid Ground State in YBaCo3FeO7(College Park, Md. : APS, 2022) Schweika, W.; Valldor, M.; Reim, J.D.; Rößler, U.K.A chiral spin liquid state is discovered in the highly frustrated, noncentrosymmetric swedenborgite compound YBaCo3FeO7, a layered kagome system of hexagonal symmetry, by advanced polarized neutron scattering from a single domain crystalline sample. The observed diffuse magnetic neutron scattering has an antisymmetric property that relates to its specific chirality, which consists of three cycloidal waves perpendicular to the c axis, forming an entity of cylindrical symmetry. Chirality and symmetry agree with relevant antisymmetric exchanges arising from broken spatial parity. Applying a Fourier analysis to the chiral interference pattern, with distinction between kagome sites and the connecting trigonal interlayer sites of threefold symmetry, the chiral spin correlation function is determined. Characteristic chiral waves originate from the trigonal sites and extend over several periods in the kagome planes. The chiral spin liquid is remarkably stable at low temperatures despite strong antiferromagnetic spin exchange. The observation raises a challenge, since the commonly accepted ground states in condensed matter either have crystalline long-range order or form a quantum liquid. We show that, within the classical theory of magnetic order, a disordered ground state may arise from chirality. The present scenario, with antisymmetric exchange acting as a frustrating gauge background that stabilizes local spin lumps, is similar to the avoided phase transition in coupled gauge and matter fields for subnuclear particles.
- ItemIntercalant-mediated Kitaev exchange in Ag3LiIr2O6(College Park, MD : APS, 2022) Yadav, Ravi; Reja, Sahinur; Ray, Rajyavardhan; van den Brink, Jeroen; Nishimoto, Satoshi; Yazyev, Oleg V.The recently synthesized Ag3LiIr2O6 has been proposed as a Kitaev magnet in proximity to the quantum spin liquid phase. We explore its microscopic Hamiltonian and magnetic ground state using many-body quantum chemistry methods and exact diagonalization techniques. Our calculations establish a dominant bond dependent ferromagnetic Kitaev exchange between Ir sites and find that the inclusion of Ag 4d orbitals in the configuration interaction calculations strikingly enhances the Kitaev exchange. Furthermore, using exact diagonalization of the nearest-neighbor fully anisotropic J−K−Γ Hamiltonian, we obtain the magnetic phase diagram as a function of further neighbor couplings. We find that the antiferromagnetic off-diagonal coupling stabilizes long range order, but the structure factor calculations suggest that the material is very close to the quantum spin liquid phase and the ordered state can easily collapse into a liquid by small perturbations such as structural distortion or bond disorder.
- ItemCold atoms in space: community workshop summary and proposed road-map(Berlin ; Heidelberg [u.a.] : Springer Open, 2022) Alonso, Iván; Alpigiani, Cristiano; Altschul, Brett; Araújo, Henrique; Arduini, Gianluigi; Arlt, Jan; Badurina, Leonardo; Balaž, Antun; Bandarupally, Satvika; Barish, Barry C.; Barone, Michele; Reguzzoni, Mirko; Richaud, Andrea; Riou, Isabelle; Rothacher, Markus; Roura, Albert; Ruschhaupt, Andreas; Sabulsky, Dylan O.; Safronova, Marianna; Saltas, Ippocratis D.; Bernabeu, Jose; Haehnelt, Martin; Salvi, Leonardo; Sameed, Muhammed; Saurabh, Pandey; Schäffer, Stefan; Schiller, Stephan; Schilling, Manuel; Schkolnik, Vladimir; Schlippert, Dennis; Schmidt, Piet O.; Schnatz, Harald; Hanımeli, Ekim T.; Bertoldi, Andrea; Schneider, Jean; Schneider, Ulrich; Schreck, Florian; Schubert, Christian; Shayeghi, Armin; Sherrill, Nathaniel; Shipsey, Ian; Signorini, Carla; Singh, Rajeev; Hawkins, Leonie; Singh, Yeshpal; Bingham, Robert; Skordis, Constantinos; Smerzi, Augusto; Sopuerta, Carlos F.; Sorrentino, Fiodor; Sphicas, Paraskevas; Stadnik, Yevgeny V.; Stefanescu, Petruta; Tarallo, Marco G.; Hees, Aurélien; Tentindo, Silvia; Tino, Guglielmo M.; Bize, Sébastien; Tinsley, Jonathan N.; Tornatore, Vincenza; Treutlein, Philipp; Trombettoni, Andrea; Tsai, Yu-Dai; Tuckey, Philip; Uchida, Melissa A.; Henderson, Victoria A.; Valenzuela, Tristan; Van Den Bossche, Mathias; Vaskonen, Ville; Blas, Diego; Verma, Gunjan; Vetrano, Flavio; Vogt, Christian; von Klitzing, Wolf; Waller, Pierre; Walser, Reinhold; Herr, Waldemar; Wille, Eric; Williams, Jason; Windpassinger, Patrick; Wittrock, Ulrich; Bongs, Kai; Wolf, Peter; Woltmann, Marian; Wörner, Lisa; Xuereb, André; Yahia, Mohamed; Herrmann, Sven; Yazgan, Efe; Yu, Nan; Zahzam, Nassim; Zambrini Cruzeiro, Emmanuel; Zhan, Mingsheng; Bouyer, Philippe; Zou, Xinhao; Zupan, Jure; Zupanič, Erik; Braitenberg, Carla; Hird, Thomas; Brand, Christian; Braxmaier, Claus; Bresson, Alexandre; Buchmueller, Oliver; Budker, Dmitry; Bugalho, Luís; Burdin, Sergey; Cacciapuoti, Luigi; Callegari, Simone; Calmet, Xavier; Hobson, Richard; Calonico, Davide; Canuel, Benjamin; Caramete, Laurentiu-Ioan; Carraz, Olivier; Cassettari, Donatella; Chakraborty, Pratik; Chattopadhyay, Swapan; Chauhan, Upasna; Chen, Xuzong; Chen, Yu-Ao; Hock, Vincent; Chiofalo, Maria Luisa; Coleman, Jonathon; Corgier, Robin; Cotter, J. P.; Michael Cruise, A.; Cui, Yanou; Davies, Gavin; De Roeck, Albert; Demarteau, Marcel; Derevianko, Andrei; Barsanti, Michele; Di Clemente, Marco; Djordjevic, Goran S.; Donadi, Sandro; Doré, Olivier; Dornan, Peter; Doser, Michael; Drougakis, Giannis; Dunningham, Jacob; Easo, Sajan; Eby, Joshua; Hogan, Jason M.; Elertas, Gedminas; Ellis, John; Evans, David; Examilioti, Pandora; Fadeev, Pavel; Fanì, Mattia; Fassi, Farida; Fattori, Marco; Fedderke, Michael A.; Felea, Daniel; Holst, Bodil; Feng, Chen-Hao; Ferreras, Jorge; Flack, Robert; Flambaum, Victor V.; Forsberg, René; Fromhold, Mark; Gaaloul, Naceur; Garraway, Barry M.; Georgousi, Maria; Geraci, Andrew; Holynski, Michael; Gibble, Kurt; Gibson, Valerie; Gill, Patrick; Giudice, Gian F.; Goldwin, Jon; Gould, Oliver; Grachov, Oleg; Graham, Peter W.; Grasso, Dario; Griffin, Paul F.; Israelsson, Ulf; Guerlin, Christine; Gündoğan, Mustafa; Gupta, Ratnesh K.; Jeglič, Peter; Jetzer, Philippe; Juzeliūnas, Gediminas; Kaltenbaek, Rainer; Kamenik, Jernej F.; Kehagias, Alex; Bass, Steven; Kirova, Teodora; Kiss-Toth, Marton; Koke, Sebastian; Kolkowitz, Shimon; Kornakov, Georgy; Kovachy, Tim; Krutzik, Markus; Kumar, Mukesh; Kumar, Pradeep; Lämmerzahl, Claus; Bassi, Angelo; Landsberg, Greg; Le Poncin-Lafitte, Christophe; Leibrandt, David R.; Lévèque, Thomas; Lewicki, Marek; Li, Rui; Lipniacka, Anna; Lisdat, Christian; Liu, Mia; Lopez-Gonzalez, J. L.; Battelier, Baptiste; Loriani, Sina; Louko, Jorma; Luciano, Giuseppe Gaetano; Lundblad, Nathan; Maddox, Steve; Mahmoud, M. A.; Maleknejad, Azadeh; March-Russell, John; Massonnet, Didier; McCabe, Christopher; Baynham, Charles F. A.; Meister, Matthias; Mežnaršič, Tadej; Micalizio, Salvatore; Migliaccio, Federica; Millington, Peter; Milosevic, Milan; Mitchell, Jeremiah; Morley, Gavin W.; Müller, Jürgen; Murphy, Eamonn; Beaufils, Quentin; Müstecaplıoğlu, Özgür E.; O’Shea, Val; Oi, Daniel K. L.; Olson, Judith; Pal, Debapriya; Papazoglou, Dimitris G.; Pasatembou, Elizabeth; Paternostro, Mauro; Pawlowski, Krzysztof; Pelucchi, Emanuele; Belić, Aleksandar; Pereira dos Santos, Franck; Peters, Achim; Pikovski, Igor; Pilaftsis, Apostolos; Pinto, Alexandra; Prevedelli, Marco; Puthiya-Veettil, Vishnupriya; Quenby, John; Rafelski, Johann; Rasel, Ernst M.; Bergé, Joel; Ravensbergen, CornelisWe summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies.
- ItemValley control by linearly polarized laser pulses: example of WSe2(Washington, DC : OSA, 2022) Sharma, S.; Elliott, P.; Shallcross, S.Electrons at the band edges of materials are endowed with a valley index, a quantum number locating the band edge within the Brillouin zone. An important question is then how this index may be controlled by laser pulses, with current understanding that it couples exclusively via circularly polarized light. Employing both tight-binding and state-of-the-art time dependent density function theory, we show that on femtosecond time scales valley coupling is a much more general effect. We find that two time separated linearly polarized pulses allow almost complete control over valley excitation, with the pulse time difference and polarization vectors emerging as key parameters for valley control. Our findings highlight the possibility of controlling coherent electronic excitation by successive femtosecond laser pulses, and offer a route towards valleytronics in two-dimensional materials.