  In QCD, the strengths of the large scale temperature dependent
chromomagnetic, $B_3, B_8$, and usual magnetic, $H$, fields spontaneously
generated in quark-gluon plasma after the deconfinement phase transition (DPT),
are estimated. The consistent at high temperature effective potential
accounting for the one-loop plus daisy diagrams is used. The heavy ion
collisions at the LHC and temperatures T not much higher than the phase
transition temperature $T_d$ are considered.
  The critical temperature for the magnetized plasma is found to be $T_d(H)$ ~
$110 - 120$ MeV. This is essentially lower compared to the zero field value
$T_d(H=0)$~ $160-180$ MeV usually discussed in the literature. Due to
contribution of quarks, the color magnetic fields act as the sources generating
H. The strengths of the fields are $B_3(T), B_8(T) \sim 10^{18} - 10^{19}G,
H(T) \sim 10^{16} - 10^{17}G$ for temperatures T ~ 160 - 220 MeV. At
temperatures $T < 110 - 120$ MeV the effective potential minimum value being
negative approaches to zero. This is signaling the absence of the background
fields and color confinement.
