I use Unified Spinor Fields (USF), to discuss the creation of magnetic monopoles during preinflation, as excitations of the quantum vacuum coming from a condensate of massive charged vector bosons. For a primordial universe with total energy $M_p$, and for magnetic monopoles created with a total Planck magnetic charge $q_M=q_P=\pm e/\sqrt{\alpha}$ and a total mass $m_M$, it is obtained after quantisation of the action that the fine-structure constant is given by: $\alpha= \frac{5}{6} \left(1- \frac{16 \,m_M}{5 \,M_p}\right) \,\left(\frac{e}{q_M}\right)^2$. If these magnetic monopoles were with total magnetic charge $q_M=\pm e$ and a small mass $m=m_M/n$, there would be a large number of small quantum magnetic monopoles which could be candidates to explain the presence of dark matter with a $30.97\,\%$ of the energy in the primordial universe at the Planck era. The case of milli-magnetically charged particles is also analysed. We demonstrate that magnetic monopoles (MM) with masses less than $3.6\times 10^3$ GeV, can exist with a very small charges of up to $10^{-14}\,e$, which are quantities of interest for searches to be performed in the ATLAS and MoEDAL experiments.