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.