The work analyzes the effect of a magnetic field
B directed along the
c axis (
B∥c) up to 9~T on the resistivity
ρ(T), fluctuation conductivity (FLC)
σ′(T) and pseudogap
Δ∗(T) in thin films of YBa
2Cu
3O
7−δ with a critical temperature of the superconducting transition
Tc=88.8~K. In contrast to previous work, where the magnetic field was directed along the
ab plane (
B∥ab), the influence of the field on the sample is stronger due to the contribution of both spin--orbit and Zeeman effects. It was found that the BEC--BCS transition temperature,
Tpair, which corresponds to the maximum of the
Δ∗(T) dependence, shifts to the region of lower temperatures with increasing
B, and the maximum value of
Δ∗(Tpair) decreases in fields
B>5~T. It was found that with increasing field, the low-temperature maximum near
T0 is smeared and disappears at
B>1~T. In addition, above the Ginzburg temperature
TG, for
B>1~T, a minimum appears on
Δ∗(T) at
Tmin, which becomes very pronounced with a subsequent increase in
B. As a result, the overall value of
Δ∗(TG) decreases noticeably, most likely due to the pair-breaking effect. At the same time,
ΔTfl and
ξc(0) increase sharply by approximately 3 times with increasing
B above 1~T. Our results confirm the possibility of the formation of a vortex state in YBa
2Cu
3O
7−δ by a magnetic field and its evolution with increasing
B.