Natural arsenic with a unique order structure: potential for new quantum materials

Area of Science:

• Materials Science
• Solid-State Physics
• Crystallography

Background:

• Arsenic (As) research is crucial for developing advanced materials.
• Understanding crystalline polymorphs is key to material property prediction.

Purpose of the Study:

• To elucidate the unique crystal structure of the third natural arsenic polymorph (Pnm2₁-As).
• To investigate the electronic structure of Pnm2₁-As using computational methods.
• To provide guidelines for next-generation material design.

Main Methods:

• Crystallographical experiments were performed to determine the atomic structure.
• First-principles computational methods were employed to analyze the electronic band structure.
• Analysis of bonding characteristics, including covalent, van der Waals, and d orbital contributions.

Main Results:

• A novel crystal structure for Pnm2₁-As was identified, featuring alternating arrangements of grey-As (semi-metallic) and black-As (semiconducting) portions at the atomic level.
• Both sd and pd hybridizations are significant for covalent and van der Waals bonding.
• Layer stacking influences van der Waals bonding and d orbital contributions.
• Charge distribution shows distinct positive and negative regions within the same element (grey-As and black-As portions).
• The material exhibits an alternating sequence of one-dimensional electron donor and acceptor portions.

Conclusions:

• Pnm2₁-As possesses a unique atomic and electronic structure with potential for novel electronic applications.
• The findings highlight the importance of charge separation and hybridization in arsenic polymorphs.
• This study provides a foundational understanding for designing new materials with tailored electronic properties based on arsenic.