Magnetostriction and thermal expansion of high-Tc magnetic superconductors REBa2Cu3O7−x (RE = Sm, Eu, Gd, Dy, Ho, Er, Tm and Y)

Abstract

Abstract The magnetostriction, parallel (λ‖) and perpendicular (λ⊥) to the applied magnetic field, has been measured in the HTC magnetic superconductors REBa2Cu3O7−x (RE = Sm, Sm, Eu, Gd, Dy, Ho, Er, Tm and Y), between 3.8 K up to above Tc with applied magnetic fields up to 2.45 T. The anisotropic magnetostriction, λt = λ‖ − λ⊥, is very weak (≤ 10-6) (except for Dy and Ho compounds, where it is large, around -120×10−6 at 4.2 K and 2.45 T), indicative, for anisotropic ions, of weak effective field penetration at the RE sites. Besides λt is of single-ion origin for Dy and Ho compounds, where performing such a test is feasible. The volume striction, ω = λ‖ + 2λ⊥, is of the same order of magnitude (around 20×10-6 ffor most of the systems, indicative of a diamagnetic effect. The thermal expansion (th.e) has been measured for this series, showing a Gruneisen T3 regime at low temperatures, and the Debye temperatures (in the range of ≅ 345–391 K) have been obtained. Noticeable, is that th.e. strains collapse to a universal temperature dependence over most of the range of temperatures explored (between around 25–200 K), indicative of a common anharmonic phonon lattice origin, that of YBa2Cu3O7−x compound.