Abstract |
Nonlinear Dependence of Velocity of
Elastic Waves on Uniaxial Tension in Single-Crystal Terbium
A.Andrianov, A.A.Korobov (Department of
Acoustics, Faculty of Physics, Moscow State University, Moscow, Russia)
e-mail:
andr@lt.phys.msu.su
The
results of experimental investigation of dependencies of a longitudinal sound
velocity on uniaxial tension in a terbium single crystal are presented. Tension
was applied along the hexagonal axis and changed in an interval 0-60 MPa. The
ultrasound was propagated perpendicularly to the hexagonal axis. Measurements
were performed in a pulse mode at room temperature. Under the pressure ~30 MPa
nonlinear dependence of sound velocity on the static pressure was observed. The
results can be treated as the following. Terbium is rare-earth metal with a
hexagonal close-packed crystallographic structure. When applying uniaxial
tension along a hexagonal axis the change of parameters of a lattice without
change of its symmetry occurs. This change causes, at pressure 30 MPa, a change
of topology of Fermi surface: electronic topological transition, which results
in anomaly in behavior of some physical properties, including velocity of
elastic waves.
Section
: 2