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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.
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