QFS2016 Book of Abstracts

Abstracts

P2.37 Notes on the Vollhardt “invariant” and phase transition in the helical itinerant magnet MnSi Stishov, Petrova Institute for High Pressure Physics of Russian Academy of Sciences,Troitsk, Moscow , Russia In this paper we argue that rounded “hills” or “valleys” demonstrated by the heat capacity, thermal expansion coefficient, and elastic module are indications of a smeared second order phase transition, which is flattened and spread out by the application of a magnetic field. As a result, some of the curves which display a temperature dependence of the corresponding quantities cross almost at a single point. Thus, the Vollhardt crossing point should not be identified with any specific energy scale. The smeared phase transition in MnSi preceding the helical first order transition most probably corresponds to the planar ferromagnetic ordering, with a small or negligible correlation between planes. At lower temperatures, the system of ferromagnetic planes becomes correlated, acquiring a helical twist. P2.38 Fermi liquid theory applied to a film on an oscillating substrate Kuorelahti(1), Tuorila(1) and Thuneberg(1) 1) University of Oulu, Theoretical Physics, Pentti Kaiteran katu 1, 90014 Oulu, Finland We consider a film of a normal-state Fermi liquid on a planar substrate. Landau’s Fermi liquid theory is applied to calculate the linear response of the film to transverse oscillation of the substrate. The response consists of a collective transverse zero sound mode, as well as incoherent quasiparticle excitations of the degenerate fermions. We calculate numerically the acoustic impedance of the film under a wide range of conditions relevant to normal state helium-3 at millikelvin temperatures. Some cases of known experiments are studied but most of the parameter range has not yet been tested experimentally.

73