Browsing by Author "Shibauchi, Takasada"

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    Nematic magnetoelastic effect contrasted between Ba(Fe1−xCox)2As2 and FeSe
    (American Physical Society, 2016) Hu, Yuwen; Ren, Xiao; Zhang, Rui; Luo, Huiqian; Kasahara, Shigeru; Watashige, Tatsuya; Shibauchi, Takasada; Dai, Pengcheng; Zhang, Yan; Matsuda, Yuji; Li, Yuan
    To elucidate the origin of nematic order in Fe-based superconductors, we report a Raman scattering study of lattice dynamics, which quantify the extent of C4-symmetry breaking, in BaFe2As2 and FeSe. FeSe possesses a nematic ordering temperature Ts and orbital-related band-energy split below Ts that are similar to those in BaFe2As2, but unlike BaFe2As2 it has no long-range magnetic order. We find that the Eg phonon-energy split in FeSe becomes substantial only well below Ts, and its saturated value is much smaller than that in BaFe2As2. Together with reported results for the Ba(Fe1−xCox)2As2 family, the data suggest that magnetism exerts a major influence on the lattice.
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    Strain-Driven Approach to Quantum Criticality in AFe2As2 with A=K, Rb, and Cs
    (American Physical Society, 2016) Eilers, Felix; Grube, Kai; Zocco, Diego A.; Wolf, Thomas; Merz, Michael; Schweiss, Peter; Heid, Rolf; Eder, Robert; Yu, Rong; Zhu, Jian-Xin; Si, Qimiao; Shibauchi, Takasada; Löhneysen, Hilbert v.
    The iron-based superconductors AFe2As2 with A=K, Rb, Cs exhibit large Sommerfeld coefficients approaching those of heavy-fermion systems. We have investigated the magnetostriction and thermal expansion of this series to shed light on this unusual behavior. Quantum oscillations of the magnetostriction allow identifying the band-specific quasiparticle masses which by far exceed the band-structure derived masses. The divergence of the Grüneisen ratio derived from thermal expansion indicates that with increasing volume along the series a quantum critical point is approached. The critical fluctuations responsible for the enhancement of the quasiparticle masses appear to weaken the superconducting state.