  The IKKT matrix model, in the large-$N$ limit, is conjectured to be a
non-perturbative definition of the ten-dimensional type IIB superstring theory.
In this work, we investigate the possibility of spontaneous breaking of the
ten-dimensional rotational symmetry in the Euclidean IKKT model. Since the
effective action, after integrating out the fermions, is inherently complex, we
use the complex Langevin dynamics to study the model. In order to evade the
singular-drift problem in the model, we add supersymmetry preserving
deformations and then take the vanishing limit of the deformations. Our
analysis suggests that the phase of the Pfaffian indeed induces the spontaneous
SO(10) symmetry breaking in the Euclidean IKKT model.
