  Despite decades of experimental and theoretical efforts, the origin of
metal-insulator transitions (MIT) in strongly-correlated materials is one of
the main longstanding problems in condensed matter physics. An archetypal
example is V2O3, where electronic, structural and magnetic phase transitions
occur simultaneously. This remarkable concomitance makes the understanding of
the origin of the MIT a challenge due to the many degrees of freedom at play.
In this work, we demonstrate that magnetism plays the key dominant role. By
acting on the magnetic degree of freedom, we reveal an anomalous behaviour of
the magnetoresistance of V2O3, which provides strong evidence that the origin
of the MIT in V2O3 is the opening of an antiferromagnetic gap in the presence
of strong electronic correlations.
