<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>UTe</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:math> : A narrow-band superconductor

We investigate the nature of the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:mn>5</a:mn> <a:mi>f</a:mi> </a:mrow> </a:math> electrons in the unconventional odd-parity superconductor <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:msub> <b:mi>UTe</b:mi> <b:mn>2</b:mn> </b:msub> </b:math> , focusing on the degree of covalency, localization versus itinerancy, and dominant electronic configuration. This is achieved using density functional theory (DFT) in combination with dynamical mean-field theory (DMFT) calculations. A key aspect of our approach is the material-specific tuning of the double-counting correction parameter, <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:msub> <c:mi>μ</c:mi> <c:mi>dc</c:mi> </c:msub> </c:math> , within the <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mrow> <d:mi>DFT</d:mi> <d:mo>+</d:mo> <d:mi>DMFT</d:mi> </d:mrow> </d:math> part. This tuning is guided by the energy dependence of photoionization cross sections in valence band photoelectron spectroscopy. The reliability of the parameters is confirmed by the accurate reproduction of the angle-resolved valence-band photoemission spectra and the <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:mrow> <e:mi mathvariant="normal">U</e:mi> <e:mspace width="0.16em"/> <e:mn>4</e:mn> <e:mi>f</e:mi> </e:mrow> </e:math> core-level data. The <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"> <h:mrow> <h:mi>DFT</h:mi> <h:mo>+</h:mo> <h:mi>DMFT</h:mi> </h:mrow> </h:math> model reveals that in <i:math xmlns:i="http://www.w3.org/1998/Math/MathML"> <i:msub> <i:mi>UTe</i:mi> <i:mn>2</i:mn> </i:msub> </i:math> <j:math xmlns:j="http://www.w3.org/1998/Math/MathML"> <j:mrow> <j:mi mathvariant="normal">U</j:mi> <j:mspace width="0.16em"/> <j:mn>5</j:mn> <j:msup> <j:mi>f</j:mi> <j:mi>n</j:mi> </j:msup> </j:mrow> </j:math> configurations with <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:mrow> <m:mi>n</m:mi> <m:mo>=</m:mo> <m:mn>1</m:mn> </m:mrow> </m:math> –4 contribute to the ground state, with the <n:math xmlns:n="http://www.w3.org/1998/Math/MathML"> <n:mrow> <n:mn>5</n:mn> <n:msup> <n:mi>f</n:mi> <n:mn>2</n:mn> </n:msup> </n:mrow> </n:math> configuration being most prevalent and an average <o:math xmlns:o="http://www.w3.org/1998/Math/MathML"> <o:mrow> <o:mn>5</o:mn> <o:mi>f</o:mi> </o:mrow> </o:math> shell filling close to 2.5. The model further suggests that the <p:math xmlns:p="http://www.w3.org/1998/Math/MathML"> <p:mrow> <p:mn>5</p:mn> <p:mi>f</p:mi> </p:mrow> </p:math> electrons form narrow bands and that charge fluctuations due to degeneracy play a role in addition to coherent valence dynamics arising from hybridization with the conduction bath. Additionally, the significance of the <q:math xmlns:q="http://www.w3.org/1998/Math/MathML"> <q:mrow> <q:mi mathvariant="normal">U</q:mi> <q:mspace width="0.16em"/> <q:mn>6</q:mn> <q:mi>d</q:mi> </q:mrow> </q:math> states in <t:math xmlns:t="http://www.w3.org/1998/Math/MathML"> <t:msub> <t:mi>UTe</t:mi> <t:mn>2</t:mn> </t:msub> </t:math> is discussed.