Fluctuation conductivity and pseudogap in HoBa2Cu3O7-δHoBa2Cu3O7-δ single crystals under pressure with transport current flowing under an angle 45° to the twin boundaries

• The substitution of Y by Ho significantly affects the charge distribution.
• The disordering in the oxygen subsystem which is affected by pressure.
• Twin boundaries are effective scattering centers of normal carriers.
• Near TcTc the conductivity is described by the Aslamasov–Larkin theory.
• Δ∗(T)Δ∗(T) demonstrates two representative maxima which disappear under pressure.

The influence of hydrostatic pressure up to 0.48 GPa on the fluctuation conductivity σ′(T)σ′(T) and pseudogap (PG) Δ∗(T)Δ∗(T) of slightly doped HoBa2Cu3O7-δHoBa2Cu3O7-δ single crystals with Tc≈Tc≈ 62 K and δ≈0.35δ≈0.35 is studied with current passing under an angle 45° to the twin boundaries. It is shown that near TcTc the conductivity σ′(T)σ′(T) is well described by the Aslamasov–Larkin and Hikami–Larkin fluctuation theories demonstrating 3D–2D crossover with the increase of temperature. Δ∗(T)Δ∗(T) displays two representative maxima at Tmax1≈219K and Tmax2≈241K likely caused by the phase stratification of the single crystal. Pressure leads to disappearance of these maxima and linear Δ∗(T)Δ∗(T) with a positive gradient at high temperatures. Essentially, with the removal of pressure the maxima are restored. The comparison of our results with those obtained for YBa2Cu3O7-δYBa2Cu3O7-δ sheds more light on the role of magnetic subsystem in the high-Tc superconductors.