Magnetic tuning of band topology evidenced by exotic quantum oscillations in the Dirac semimetal <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>EuMnSb</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>

Interplay between magnetism and electronic band topology is of central current interest in topological matter research. We use quantum oscillations as powerful tool to probe the evolution Dirac semimetal EuMnSb$_2$. The Eu local 4f magnetic moments display different antiferromagnetic states below 25 K a field-polarized phase above 16 T. Upon cooling from 65 into state, an exotic temperature dependent shift oscillation peaks arises, accompanied by development non-zero Berry huge unconventional splitting oscillations. Band-structure calculations confirm change trivial non-trivial induced ferromagnetic classifying EuMnSb$_2$ unique semimetal.