Unconventional Superconductivity; Neutron Scattering; SANS; Vortex lattice; Magnetism; condensed matter; superconductivity; unconventional superconductors; heavy fermions; muSR; solid state physics; strongly correlated electron systems
Egetenmeyer N, Gavilano JL, Maisuradze A, Gerber S, MacLaughlin DE, Seyfarth G, Andreica D, Desilets-Benoit A, Bianchi AD, Baines C, Khasanov R, Fisk Z, Kenzelmann M. (2012), Direct Observation of the Quantum Critical Point in Heavy Fermion CeRhSi3, in PHYSICAL REVIEW LETTERS
, 108(17), 177204-1-177204-5.
Chang J, White J. S., Laver M., Bowel C. J., Brown S. P., Holmes A. T., Maecheler L., Sträsle S., Gilardi L., Gerber S., Kurosowa N., Momono N., Oda M., Ido M., Lipscombe O. J., Hayden S. M., Dewhurst C. D., Vavrin R., Gavilano J. L., Kohlbrecher J., Forgan E. M., Mesot J. (2012), Spin Density Wave Induced Disordering of the Vortex Lattice in Superconducting La2-xSrxCu4, in Physical Review B
, 85(13), 134520-1-134520-7.
Das P., White J. S., Holmes A. T., Gerber S., Forgan E. M., Bianchi A. D., Kenzelmann M., Zolliker M., Gavilano J. L., Bauer E. D., Sarrao J. L., Petrovic C., Eskildsen M. R. (2012), Vortex Lattice Studies in CeCoIn5 with H Perpendicular to c, in Physical Review Letters
, 108(8), 087002-1-087002-5.
Biswas P K, Lees M R, Balakrishnan G, Liao D Q, Keeble D S, Gavilano J L, Egetenmeyer N, Dewhurst C D, Paul D McK (2012), First-order reorientation transition of the flux-line lattice in CaAlSi., in Physical review letters
, 108(7), 077001-1-077001.
White JS, Heslop RW, Holmes AT, Forgan EM, Hinkov V, Egetenmeyer N, Gavilano JL, Laver M, Dewhurst CD, Cubitt R, Erb A (2011), Magnetic-field-induced nonlocal effects on the vortex interactions in twin-free YBa2Cu3O7, in PHYSICAL REVIEW B
, 84(10), 104519-1-104519-17.
Kawano-Furukawa H, Bowell CJ, White JS, Heslop RW, Cameron AS, Forgan EM, Kihou K, Lee CH, Iyo A, Eisaki H, Saito T, Fukazawa H, Kohori Y, Cubitt R, Dewhurst CD, Gavilano JL, Zolliker M (2011), Gap in KFe2As2 studied by small-angle neutron scattering observations of the magnetic vortex lattice, in PHYSICAL REVIEW B
, 84(2), 0274507-1-0274507-8.
Kawasaki Y, Gavilano JL, Keller L, Schefer J, Christensen NB, Amato A, Ohno T, Kishimoto Y, He ZZ, Ueda Y, Itoh M (2011), Magnetic structure and spin dynamics of the quasi-one-dimensional spin-chain antiferromagnet BaCo2V2O8, in PHYSICAL REVIEW B
, 83(6), 064421-1-064421-6.
Li YA, Egetenmeyer N, Gavilano JL, Barisic N, Greven M (2011), Magnetic vortex lattice in HgBa2CuO4+delta observed by small-angle neutron scattering, in PHYSICAL REVIEW B
, 83(5), 054507-1-054507-5.
Lewtas HJ, Boothroyd AT, Rotter M, Prabhakaran D, Muller H, Le MD, Roessli B, Gavilano J, Bourges P (2010), Magnetic excitations in multiferroic LuMnO3 studied by inelastic neutron scattering, in PHYSICAL REVIEW B
, 82(18), 184420-1-184420-7.
Kenzelmann M, Gerber S, Egetenmeyer N, Gavilano JL, Strassle T, Bianchi AD, Ressouche E, Movshovich R, Bauer ED, Sarrao JL, Thompson JD (2010), Evidence for a Magnetically Driven Superconducting Q Phase of CeCoIn5, in PHYSICAL REVIEW LETTERS
, 104(12), 127001-1-127001-4.
Kenzelmann M, Gerber S, Egetenmeyer N, Gavilano J L, Strässle Th, Bianchi A D, Ressouche E, Movshovich R, Bauer E D, Sarrao J L, Thompson J D (2010), Evidence for a magnetically driven superconducting Q phase of CeCoIn5., in Physical review letters
, 104(12), 127001-127001.
White JS, Hinkov V, Heslop RW, Lycett RJ, Forgan EM, Bowell C, Strassle S, Abrahamsen AB, Laver M, Dewhurst CD, Kohlbrecher J, Gavilano JL, Mesot J, Keimer B, Erb A (2009), Fermi Surface and Order Parameter Driven Vortex Lattice Structure Transitions in Twin-Free YBa2Cu3O7, in PHYSICAL REVIEW LETTERS
, 102(9), 097001-1-097001-4.
White J S, Hinkov V, Heslop R W, Lycett R J, Forgan E M, Bowell C, Strässle S, Abrahamsen A B, Laver M, Dewhurst C D, Kohlbrecher J, Gavilano J L, Mesot J, Keimer B, Erb A (2009), Fermi surface and order parameter driven vortex lattice structure transitions in twin-free YBa2Cu3O7., in Physical review letters
, 102(9), 097001-097001.
We request funding to support two Ph.D. students to experimentally study the interplay of magnetism and superconductivity in selected unconventional superconductors. Of particular interest in this project are phase transitions between different superconducting states, particularly those that are related to changes in spatial structures of the superconducting state with magnetic field. Examples include vortex lattices that appear in type II superconductors in the presence of external magnetic fields and, the recently found Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state in Pauli-limited, type II superconductors, characterized by a spatial modulation of the superconducting order parameter.1,2 Also of interest are novel magnetic fluctuations and long-range magnetic order in the superconducting phase. The symmetry of the superconducting gap in unconventional superconductivity excludes that the Cooper formation is mediated by phonons. There is strong evidence that unconventional superconductivity is mediated by spin fluctuations. We expect that this leads to interesting coupling phenomena of magnetism and superconductivity, at high magnetic fields, H, where the electrons condense into Cooper pairs as H decreases below Hc2.We will use small angle neutron scattering (SANS) and triple-axis neutron instruments for our studies. The instruments SANS1 and SANS2 at PSI are ideal for our experiments due to the world-wide unique availability of dilution fridge temperatures and high horizontal fields up to H=11 T, while the triple-axis spectrometer RITA-II at PSI is ideal for high-field diffraction studies. Inelastic studies are planned to be carried out at the ILL, Grenoble. Our research program will focus on CeCoIn5, Cd-doped CeCoIn5, UBe13, URu2Si2 and LaBiPt by neutron scattering techniques. These measurements will be complemented, where appropriate, with magnetization measurements and muon-spin rotation measurements. The samples required for this project are high quality single crystals that will be provided mostly by Prof. Andrea Bianchi. Recent successful studies on the vortex lattice by Prof. M. Kenzelmann and Prof. A. Bianchi on CeCoIn5 using SANS1 at PSI have shown that the available expertise and tools are most adequate for our project. The formal adviser of the two Ph.D. students will be Prof. Joel Mesot, ETHZ & PSI._____________________________1 M. Franz, I. Affleck, and M.H. Amin, Theory of Equilibrium Flux Lattices in Unconventional Superconductors, Phys. Rev. Lett., 79, 1555 (1997).2 Y. Matsuda and H. Shimahara, Fulde-Ferrell-Larkin-Ovchinnikov State in Heavy Fermion Superconductors, J. Phys. Soc. Jap. 76, 051005 (2007).