Stabilization of U 5f2 configuration in UTe2 through U 6d dimers in the presence of Te2 …

We investigate the topological superconductor candidate <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>UTe</a:mi><a:mn>2</a:mn></a:msub></a:math> using high-resolution valence-band resonant inelastic x-ray scattering at the U <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>M</b:mi><b:mrow><b:mn>4</b:mn><b:mo>,</b:mo><b:mn>5</b:mn></b:mrow></b:msub></b:math> edges. We observe atomiclike low-energy excitations that support the correlated nature of this unconventional superconductor. These excitations originate from the U <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mrow><c:mn>5</c:mn><c:msup><c:mi>f</c:mi><c:mn>2</c:mn></c:msup></c:mrow></c:math> configuration, which is unexpected since the short Te2-Te2 distances exclude Te2 being <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mn>2</d:mn><d:mo>−</d:mo></d:math>. By utilizing the photoionization cross-section dependence of the photoemission spectra in combination with band structure calculations, we infer that the stabilization of the U <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:mrow><e:mn>5</e:mn><e:msup><e:mi>f</e:mi><e:mn>2</e:mn></e:msup></e:mrow></e:math> configuration is due to the U <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:mrow><f:mn>6</f:mn><f:mi>d</f:mi></f:mrow></f:math> bonding states in the U dimers acting as a charge reservoir. Our results emphasize that the description of the physical properties should commence with a <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"><g:mrow><g:mn>5</g:mn><g:msup><g:mi>f</g:mi><g:mn>2</g:mn></g:msup></g:mrow></g:math> ansatz. Published by the American Physical Society 2024