DCMPMS Seminars

Fermi surface in bulk SmB6 from electronic structure calculations

by Dr. Anup Pradhan Sakhya (Visiting Post-doctoral Fellow, DCMP&MS, T.I.F.R., Mumbai)

Tuesday, April 9, 2019 from to (Asia/Kolkata)
at AG80
Description
We studied the electronic structure of SmB6 believed to be a Kondo insulator, employing density functional theory (DFT) with different approximations of the exchange correlation functionals such as generalized gradient approximation (GGA), modified Becke-Johnson potential (mBJ) etc. The role of spin-orbit coupling (SOC) and electron correlation (U = correlation strength) in the electronic structure has also been investigated. The results with different approximations and different interaction parameters leads to significantly different electronic structures. We find that GGA+SOC+U (U= 7 eV and exchange term, J =0.83 eV) provides the best description of the Sm 4f multiplets observed in angle-resolved photoemission spectroscopy (ARPES) data. All the calculations converge to a metallic ground state indicating robustness of the bulk metallic ground state although SmB6 was originally predicted to be one of the first Kondo insulator discovered. The Fermi surface plots exhibit electron pockets around X-point having dominant Sm 4f character and hole pockets around ΓX line having mixed character; the observation of these Fermi surfaces is consistent with the recent quantum oscillation measurements. In addition to primarily Sm 4f contributions observed at the Fermi level, we discover significantly large contribution from B 2p states compared to weak Sm 5d contributions. This suggests important role of B 2p - Sm 4f hybridization in the exotic physics of this system.