An original interferometer-based setup for measurements of length of
needle-like samples is developed, and thermal expansion of o-TaS3 crystals
is studied. Below the Peierls transition the temperature hysteresis of length
L is observed, the width of the hysteresis loop δL/L being up to 5⋅10−5. The behavior of the loop is anomalous: the length changes so
that it is in front of its equilibrium value. The hysteresis loop couples with
that of conductivity. The sign and the value of the length hysteresis are
consistent with the strain dependence of the charge-density waves (CDW) wave
vector. With lowering temperature down to 100 K the CDW elastic modulus grows
achieving a value comparable with the lattice Young modulus. Our results could
be helpful in consideration of different systems with intrinsic
superstructures.Comment: 4 pages, 3 figures. Phys. Rev. Lett., accepted for publicatio