QFS 2016 Book of Abstracts

Abstracts

I1.3 Quantum criticality and novel phases in heavy fermion metals Silke Paschen Vienna University of Technology, Austria Heavy fermion materials are prototype systems to study quantum criticality: the application of non-thermal control parameters such as magnetic field or pressure frequently induces a continuous phase transition at absolute zero in temperature. Quantum fluctuations emerging from such a ”quantum critical point” (QCP) lead to exotic behaviour that cannot be accounted for by Landau Fermi liquid theory and is thus called non-Fermi liquid behaviour. Frequently, new phases, including unconventional superconductivity, form in the vicinity of a QCP. After an overview of the field I will present recent efforts to extend the temperature scale of such studies to ultralow temperatures using cooling by nuclear demagnetization. O1.7 One-Dimensional Liquid 4 He and Hard-Core Systems: Dynamical Properties beyond Luttinger-Liquid Theory Bertaina Gianluca(1), Motta Mario(2), Rossi Maurizio(3,4,5), Vitali Ettore(2), Galli Davide Emilio (1) (1) Universit`a degli Studi di Milano, Dipartimento di Fisica, via Celoria 16, I-20133 Milano, Italy (2) The College of William and Mary, Department of Physics, Williamsburg, Virginia 23187, USA (3) Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy (4) International Center for Theoretical Physics (ICTP), Strada Costiera 11, I-34154 Trieste, Italy (5) Universit`a degli Studi di Padova, Dipartimento di Fisica e Astronomia, via Marzolo 8, I-35131 Padova, Italy Low-energy properties of one-dimensional liquid 4 He can be described by Luttinger-liquid theory. By means of quantum Monte Carlo and analytic continuation techniques, we compute the density structure factor also at higher energies at zero temperature [1]. Such quantity reveals the evolution from a highly compressible liquid to a quasisolid regime, manifesting a pseudo-particle-hole continuum typical of fermionic systems. At high density, we observe a novel behavior that can be interpreted with the hard-rods model, whose dynamics we investigate. Our results are compatible with some predictions by nonlinear Luttinger-liquid theory. [1] G. Bertaina et al., Phys. Rev. Lett. 116, 135302 (2016)

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