A new form of (unexpected) Dirac fermions in the strongly-correlated cerium monopnictides

Abstract

Discovering Dirac fermions with novel properties has become an important front in condensed matter and materials sciences. Here, we report the observation of unusual Dirac fermion states in a strongly-correlated electron setting, which are uniquely distinct from those of graphene and conventional topological insulators. In strongly-correlated cerium monopnictides, we find two sets of highly anisotropic Dirac fermions that interpenetrate each other with negligible hybridization, and show a peculiar four-fold degeneracy where their Dirac nodes overlap. Despite the lack of protection by crystalline or time-reversal symmetries, this four-fold degeneracy is robust across magnetic phase transitions. Comparison of these experimental findings with our theoretical calculations suggests that the observed surface Dirac fermions arise from bulk band inversions at an odd number of high-symmetry points, which is analogous to the band topology which describes a ${\mathbb{Z}}_2$-topological phase. Our findings open up an unprecedented and long-sought-for platform for exploring novel Dirac fermion physics in a strongly-correlated semimetal.

References in corpus (1)

• Surface States of the Topological Insulator Bi_{1-x}Sb_x

Cited by in corpus (14)

• Multiple Dirac cones at the surface of the topological metal LaBi
• Weyl-Kondo Semimetal in Heavy Fermion Systems
• Topological Insulators from Group Cohomology
• Possible Weyl fermions in the magnetic Kondo system CeSb
• Experimental determination of the topological phase diagram in Cerium monopnictides
• Origin of the Extremely Large Magnetoresistance in the Semimetal YSb
• Extremely large magnetoresistance in topologically trivial semimetal $\alpha$-WP${}_2$
• Tunable Electronic Structure and Topological Properties of $LnPn$ ($Ln$=Ce, Pr, Gd, Sm, Yb; $Pn$=Sb, Bi)
• Possible devil's staircase in the Kondo lattice CeSbSe
• Unusual change in the Dirac-cone energy band upon two-step magnetic transition in CeBi
• Magnetic-field-induced nontrivial electronic state in the Kondo-lattice semimetal CeSb
• Probing the Origin of Extreme Magnetoresistance in Pr/Sm Mono-Antimonides/Bismuthides
• Band engineering of a magnetic thin film rare earth monopnictide
• Comparative study of the compensated semi-metals LaBi and LuBi : A first-principles approach