Uncovering surface states of the Dirac semimetal <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>BaMg</mml:mi> <mml:mn>2</mml:mn> </mml:msub> <mml:msub> <mml:mi>Bi</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:

<a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:msub> <a:mi>BaMg</a:mi> <a:mn>2</a:mn> </a:msub> <a:msub> <a:mi>Bi</a:mi> <a:mn>2</a:mn> </a:msub> </a:mrow> </a:math> is a Dirac semimetal characterized by a simple Dirac cone crossing the Fermi level at the center of the Brillouin zone, protected by <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:msub> <b:mi>C</b:mi> <b:mn>3</b:mn> </b:msub> </b:math> rotational symmetry. Together with its Sr-based analog <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:msub> <c:mi>SrMg</c:mi> <c:mn>2</c:mn> </c:msub> <c:msub> <c:mi>Bi</c:mi> <c:mn>2</c:mn> </c:msub> </c:mrow> </c:math> , it has been proposed as a promising candidate for a chemically driven topological switch: while <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mrow> <d:msub> <d:mi>SrMg</d:mi> <d:mn>2</d:mn> </d:msub> <d:msub> <d:mi>Bi</d:mi> <d:mn>2</d:mn> </d:msub> </d:mrow> </d:math> is an insulator, <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:mrow> <e:msub> <e:mi>BaMg</e:mi> <e:mn>2</e:mn> </e:msub> <e:msub> <e:mi>Bi</e:mi> <e:mn>2</e:mn> </e:msub> </e:mrow> </e:math> exhibits nontrivial topological features. A detailed understanding of its electronic structure is essential to elucidate its electronic and transport properties. Previous photoemission studies confirmed the Dirac nature of <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"> <f:mrow> <f:msub> <f:mi>BaMg</f:mi> <f:mn>2</f:mn> </f:msub> <f:msub> <f:mi>Bi</f:mi> <f:mn>2</f:mn> </f:msub> </f:mrow> </f:math> , but were limited to high photon energies, which hindered direct comparison with density functional theory calculations (DFT), due to reduced resolution and higher-frequency matrix-element modulation in that regime. In this work, we combine high-resolution angle-resolved photoemission spectroscopy and DFT calculations to get full insight into the valence band states, providing a comprehensive picture of the low-energy electronic structure. Our measurements reveal the presence of previously unobserved surface states. We found that they are topologically trivial, but they unlock a more comprehensive understanding of the material's behavior, reconciling previous discrepancies between experiment and theory.