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Author: Kim, C. × Type: Article ×

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    Single layer graphene induces load-bearing molecular layering at the hexadecane-steel interface
    (Bristol : Institute of Physics Publishing, 2019) Krämer, G.; Kim, C.; Kim, K.-S.; Bennewitz, R.
    The influence of a single layer graphene on the interface between a polished steel surface and the model lubricant hexadecane is explored by high-resolution force microscopy. Nanometer-scale friction is reduced by a factor of three on graphene compared to the steel substrate, with an ordered layer of hexadecane adsorbed on the graphene. Graphene furthermore induces a molecular ordering in the confined lubricant with an average range of 4-5 layers and with a strongly increased load-bearing capacity compared to the lubricant on the bare steel substrate. © 2019 IOP Publishing Ltd.
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    Momentum dependent dxz/yz band splitting in LaFeAsO
    (Berlin : Springer Nature, 2020) Huh, S.S.; Kim, Y.S.; Kyung, W.S.; Jung, J.K.; Kappenberger, R.; Aswartham, S.; Büchner, B.; Ok, J.M.; Kim, J.S.; Dong, C.; Hu, J.P.; Cho, S.H.; Shen, D.W.; Denlinger, J.D.; Kim, Y.K.; Kim, C.
    The nematic phase in iron based superconductors (IBSs) has attracted attention with a notion that it may provide important clue to the superconductivity. A series of angle-resolved photoemission spectroscopy (ARPES) studies were performed to understand the origin of the nematic phase. However, there is lack of ARPES study on LaFeAsO nematic phase. Here, we report the results of ARPES studies of the nematic phase in LaFeAsO. Degeneracy breaking between the dxz and dyz hole bands near the Γ and M point is observed in the nematic phase. Different temperature dependent band splitting behaviors are observed at the Γ and M points. The energy of the band splitting near the M point decreases as the temperature decreases while it has little temperature dependence near the Γ point. The nematic nature of the band shift near the M point is confirmed through a detwin experiment using a piezo device. Since a momentum dependent splitting behavior has been observed in other iron based superconductors, our observation confirms that the behavior is a universal one among iron based superconductors.