Revealing electronic correlations in YNi₂B₂C using photoemission spectroscopy.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Low-energy electronic structure dictates material properties.
• Angle-resolved photoemission spectroscopy (ARPES) is vital for measuring electronic structure.
• Interpreting ARPES data, especially soft X-ray ARPES (SX-ARPES), can be challenging.

Purpose of the Study:

• To decipher the SX-ARPES spectra of the superconductor YNi2B2C.
• To investigate the electronic correlations in YNi2B2C.
• To establish the necessity of advanced computational methods for accurate spectral interpretation.

Main Methods:

• Density Functional Theory (DFT) combined with a one-step model of photoemission.
• Full potential Korringa-Kohn-Rostoker (FP-KKR) method.
• Dynamical Mean Field Theory (DMFT) applied to Ni d-states within DFT (DFT+DMFT).

Main Results:

• The analysis revealed moderate electronic correlations beyond standard semilocal DFT approximations.
• DFT+DMFT calculations with specific Coulomb (U=3.0 eV) and exchange (J=0.9 eV) parameters accurately reproduced the experimental SX-ARPES spectra.
• The study highlights the importance of including electronic correlations for understanding YNi2B2C.

Conclusions:

• Standard DFT approximations are insufficient for fully describing the electronic structure of YNi2B2C.
• Advanced methods like DFT+DMFT are essential for interpreting SX-ARPES spectra accurately.
• The findings provide deeper insights into the electronic properties of this quaternary borocarbide superconductor.