Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 50: Quantum-Critical Phenomena I
TT 50.8: Hauptvortrag
Mittwoch, 14. März 2018, 11:30–12:00, H 3005
Critical Phonon Softening Near a Structural Instability at boldT = 0normal — •Oliver Stockert — Max-Planck-Institut CPfS, Dresden
While lots of studies have focused on magnetic quantum critical points, remarkably little is known about structural instabilities occurring at T = 0. Technological improvements made it recently possible to observe low-energy phonons and phonon softening by high-resolution inelastic x-ray scattering (IXS) with energy resolution of about 1 meV, i.e. quite similar to inelastic neutron scattering (INS). We have studied in detail the lattice dynamics in the quantum critical charge density wave system Lu(Pt1−xPdx)2In [1] using both INS and high-resolution IXS. Superconductivity in this system displays a pronounced maximum of the transition temperature in the vicinity of the structural quantum criticality at xc ≈ 0.6 [1]. We were able to trace the softening of the critical phonon modes down to energies of < 0.5 meV using INS and even IXS. Importantly, the results of both methods match, showing the capabilities of IXS. The precise information on the temperature evolution of the critical modes provided by these experiments is essential to get an understanding of the unusual properties observed in such quantum critical systems, e.g. for the emergence of unconventional superconductivity.
[1] T. Gruner et al., Nature Phys. 13, 967 (2017).
*In collaboration with T. Gruner, S. Lucas, Z. Huesges, K. Kaneko, S. Tsutsui, K. Schmalzl, M. Koza, A. Hoser, M. Reehuis, C. Geibel.