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DDC: 530 × Subject: Three orders of magnitude ×

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    Robust nuclear hyperpolarization driven by strongly coupled nitrogen vacancy centers
    (Melville, NY : American Inst. of Physics, 2021) Wunderlich, Ralf; Staacke, Robert; Knolle, Wolfgang; Abel, Bernd; Haase, Jürgen; Meijer, Jan
    Nuclear magnetic resonance techniques are widely used in the natural sciences but they lack sensitivity. Therefore, large sample volumes or long measurement times are necessary. In this work, we investigate the polarization of bulk 13C nuclei in a diamond above the thermal equilibrium at room temperature. Previously studied mechanisms utilize direct coupling to nitrogen vacancy centers or the additional assistance of substitutional nitrogen impurities for this purpose. We exploit strongly coupled nitrogen vacancy centers as polarization sources. We study two approaches to transfer the optically induced polarization of the electron spins of the nitrogen vacancy centers to nearby nuclear spins. First, the electron-nuclear polarization transfer is achieved by energy matching conditions or, second, by magnetic field sweeps inducing Landau–Zener-like transitions. Simulations according to a quantum mechanical system consisting of two coupled nitrogen vacancy centers and a weakly coupled 13C spin show an excellent agreement with the experimental data. Both approaches allow a reduction of the measurement time by roughly three orders of magnitude.
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    Formation of heavy d-electron quasiparticles in Sr3Ru2O7
    (Milton Park : Taylor & Francis, 2013) Allan, M.P.; Tamai, A.; Rozbicki, E.; Fischer, M.H.; Voss, J.; King, P.D.C.; Meevasana, W.; Thirupathaiah, S.; Rienks, E.; Fink, J.; Tennant, D.A .; Perry, R.S.; Mercure, J.F.; Wang, M.A.; Lee, Jinho; Fennie, C.J.; Kim, E.A.; Lawler, M.J.; Shen, K.M.; Mackenzie, A.P.; Shen, Z.X.; Baumberger, F.
    The phase diagram of Sr3Ru2O7 shows hallmarks of strong electron correlations despite the modest Coulomb interaction in the Ru 4d shell. We use angle-resolved photoelectron spectroscopy measurements to provide microscopic insight into the formation of the strongly renormalized heavy d-electron liquid that controls the physics of Sr3Ru2O7. Our data reveal itinerant Ru 4d-states confined over large parts of the Brillouin zone to an energy range of <6 meV, nearly three orders of magnitude lower than the bare band width. We show that this energy scale agrees quantitatively with a characteristic thermodynamic energy scale associated with quantum criticality and illustrate how it arises from a combination of back-folding due to a structural distortion and the hybridization of light and strongly renormalized, heavy quasiparticle bands. The resulting heavy Fermi liquid has a marked k-dependence of the renormalization which we relate to orbital mixing along individual Fermi surface sheets.