Unidirectional Rashba spin splitting in single layer WS_2(1-x)Se_2xalloy

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Two-dimensional (2D) layered semiconductors, like transition metal dichalcogenides, are crucial for their tunable band gaps and unique spin-valley physics.
• These materials offer potential for novel electronic and spintronic devices due to their distinct physical properties.

Purpose of the Study:

• To investigate the electronic properties of single-layer WS_1.4Se_0.6 alloys.
• To explore the relationship between electronic band structure, spin splitting, and in-plane polarization in these 2D materials.

Main Methods:

• Angle-resolved photoemission spectroscopy (ARPES) was used to probe the electronic band structure.
• Piezo force microscopy (PFM) and photoluminescence (PL) were employed to investigate in-plane polarization and strain.

Main Results:

• A unidirectional Rashba spin splitting with a giant Rashba parameter (2.8 ± 0.7 eV Å) was observed in the WSSe alloy.
• This spin splitting is directly linked to an in-plane polarization and distorted crystal structure, influenced by S/Se atomic ordering and tensile strain.

Conclusions:

• The WSSe 2D alloy demonstrates a unique interplay between semiconducting properties, in-plane spontaneous polarization, and giant Rashba spin-splitting.
• These findings suggest significant potential for applications in next-generation electronics, piezotronics, and spintronics.