Gap-anisotropic model for the narrow-Gap kondo insulators

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Kondo insulating materials exhibit unique electronic properties due to strong electron correlations.
• Understanding the formation of hybridization gaps in these materials is crucial for their technological applications.
• Previous models did not fully explain the nodal structure of the hybridization gap in specific cerium compounds.

Purpose of the Study:

• To present a theoretical framework for the dynamical generation of a hybridization gap with nodes.
• To explain the role of Hund's interactions in shaping the electronic configuration of cerium ions.
• To elucidate the selection of a nodal Kondo semimetal state in low-symmetry crystals.

Main Methods:

• Theoretical modeling of electronic interactions in cerium-based Kondo insulators.
• Analysis of Hund's interactions acting on virtual 4f(2) configurations.
• Investigation of Weiss field generation and its coupling to ionic shape.

Main Results:

• A theory is presented that accounts for the dynamical generation of a hybridization gap with nodes.
• Hund's interactions dynamically select the cerium ion's shape via a generated Weiss field.
• A nodal Kondo semimetal state is identified as the lowest energy configuration in low-symmetry crystals.

Conclusions:

• The proposed theory successfully explains the observed hybridization gap with nodes in CeNiSn and CeRhSb.
• Dynamical selection of ionic shape through Hund's interactions is a key mechanism.
• The findings provide a new understanding of electronic structure in correlated materials.