Strain-induced topological charge control in multifold fermion systems.

Area of Science:

• Condensed matter physics
• Materials science
• Topological materials

Background:

• Multifold fermion systems possess unique free fermionic excitations.
• These systems exhibit unconventional physical properties not seen in high-energy physics.
• Controlling topological charges in these materials is crucial for understanding their behavior.

Purpose of the Study:

• To investigate the effect of strain engineering on topological charges in CoSi, a multifold fermion candidate.
• To explore the relationship between rotational symmetry, multifold fermions, and Weyl points.
• To demonstrate a method for tuning the topological properties of multifold fermion systems.

Main Methods:

• First-principles calculations (density functional theory).
• Introduction of a low-energy effective model.
• Analysis of topological charge distribution under strain.

Main Results:

• Strain engineering effectively controls topological charge distribution in CoSi.
• Breaking rotational symmetry via strain eliminates multifold fermions.
• The destruction of multifold fermions leads to the emergence of Weyl points.

Conclusions:

• Strain engineering is a viable strategy for manipulating topological properties in multifold fermion materials.
• The study provides a pathway to tune material properties by controlling symmetry.
• Findings offer insights into the creation of novel topological phases.