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dc.contributor.authorGrønsleth, Martin Sigurdnb_NO
dc.date.accessioned2014-12-19T13:16:07Z
dc.date.available2014-12-19T13:16:07Z
dc.date.created2008-05-20nb_NO
dc.date.issued2008nb_NO
dc.identifier124339nb_NO
dc.identifier.isbn978-82-471-7894-2nb_NO
dc.identifier.urihttp://hdl.handle.net/11250/246201
dc.description.abstractThis thesis presents four research papers. In the first three papers we have derived analytical results for the transport properties in unconventional superconductors and ferromagnetic systems with multiple broken symmetries. In Paper I and parts of Paper II we have studied tunneling transport between two non-unitary ferromagnetic spin-triplet superconductors, and found a novel interplay between ferromagnetism and superconductivity manifested in the Josephson effect as a spin- and charge-current in the absence of an applied voltage across the junction. The critical amplitudes of these currents can be adjusted by the relative magnetization direction on each side of the junction. Furthermore, in Paper II, we have found a way of controlling a spin-current between two ferromagnets with spin-orbit coupling. Paper III considers a junction consisting of a ferromagnet and a non-unitary ferromagnetic superconductor, and we show that the conductance spectra contains detailed information about the superconducting gaps and pairing symmetry of the Cooper-pairs. In the last paper we present a Monte Carlo study of an effective Hamiltonian describing orbital currents in the CuO2 layers of high-temperature superconductive cuprates. The model features two intrinsically anisotropic Ising models, coupled through an anisotropic next-nearest neighbor interaction, and an Ashkin–Teller nearest neighbor fourth order coupling. We have studied the specific heat anomaly, as well as the anomaly in the staggered magnetization associated with the orbital currents and its susceptibility. We have found that in a limited parameter regime, the specific heat anomaly is substantially suppressed, while the susceptibility has a non-analytical peak across the order-disorder transition. The model is therefore a candidate for describing the breakup of hidden order when crossing the pseudo-gap line on the under-doped side in the phase diagram of high-temperature superconductors.nb_NO
dc.languageengnb_NO
dc.publisherFakultet for naturvitenskap og teknologinb_NO
dc.relation.ispartofseriesDoktoravhandlinger ved NTNU, 1503-8181; 2008:95nb_NO
dc.relation.haspartGrønsleth, Martin Sigurd; Linder, J.; Børven, J.-M.; Sudbø, A.. Interplay between ferromagnetism and superconductivity in tunneling currents. PHYSICAL REVIEW LETTERS. 97(14): 147002, 2006.nb_NO
dc.relation.haspartLinder, J.; Grønsleth, M.S.; Sudbø, A.. Tunneling currents in ferromagnetic systems with multiple broken symmetries. PHYSICAL REVIEW B. 75(2): 024508, 2007.nb_NO
dc.relation.haspartLinder, J.; Grønsleth, M.S.; Sudbø, A.. Conductance spectra of ferromagnetic superconductors: Quantum transport in a ferromagnetic metal/non-unitary ferromagnetic superconductor junction. PHYSICAL REVIEW B. 75(5): 054518, 2007.nb_NO
dc.relation.haspartGrønsleth, M.S.; Nilssen, T.B.; Dahl, E.K.; Varma, C.M.; Sudbø, A.. Specific heat, order parameter, and magnetic susceptibility from fluctuating orbital currents in high-Tc superconducting cuprates. .nb_NO
dc.titleTheoretical Studies of Unconventional Superconductorsnb_NO
dc.typeDoctoral thesisnb_NO
dc.contributor.departmentNorges teknisk-naturvitenskapelige universitet, Fakultet for naturvitenskap og teknologi, Institutt for fysikknb_NO
dc.description.degreePhD i fysikknb_NO
dc.description.degreePhD in Physicsen_GB


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