Topological tuning in three-dimensional dirac semimetals.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Three-dimensional Dirac semimetals host unique electronic properties governed by Dirac fermions.
• Understanding the interplay between bulk and surface states is crucial for novel electronic applications.

Purpose of the Study:

• To investigate the topological phase transitions in Dirac semimetals.
• To explore the tunability of bulk Dirac points via compositional changes.
• To analyze the relationship between band ordering and topological transitions.

Main Methods:

• First-principles calculations.
• Density functional theory (DFT).
• Coherent potential approximation (CPA).

Main Results:

• A topological phase transition was identified in Na_{3}Bi_{1-x}Sb_{x} and Cd_{3}[As_{1-x}P_{x}]_{2} alloys.
• Compositional tuning (Sb or P concentration) drives the transition from Dirac semimetal to trivial insulator.
• The position of bulk Dirac points in reciprocal space is engineerable.
• The topological phase transition coincides with a reversal of conduction and valence band ordering.

Conclusions:

• Compositional engineering offers a pathway to control topological properties in Dirac semimetals.
• The observed phase transition and band reversal provide fundamental insights into Dirac semimetal physics.
• These findings pave the way for designing novel quantum materials with tailored electronic characteristics.