Extremely large magnetoresistance in twisted intertwined graphene spirals

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Extremely large magnetoresistance (XMR) is crucial for spintronic devices like magnetic sensors and memory.
• XMR typically occurs in Weyl semimetals with high conductivity and electron-hole symmetry.
• Graphene moiré systems offer a new platform for exploring topological phenomena.

Purpose of the Study:

• To investigate XMR in a newly developed three-dimensional intertwined twisted graphene spiral (TGS) system.
• To understand the role of topological structure and crystal quality in achieving XMR.
• To explore the electronic properties and potential applications of TGS.

Main Methods:

• Fabrication of 3D TGS with a specific rotation angle (7.3°) by manipulating the screw dislocation axis.
• Measurement of magnetoresistance at varying magnetic fields (up to 14 T) and temperatures (down to 2 K).
• Analysis of the electronic properties and phase transitions within the TGS system.

Main Results:

• Achieved an unprecedented magnetoresistance of 1.7 × 10⁷% at 14 T and 2 K.
• Observed a temperature-induced metal-insulator transition, triggered by magnetic fields above 0.1 T.
• Suggested the presence of complex, correlated states in the 3D Landau levels of the TGS system.

Conclusions:

• Engineered topological structures in 2D layered moiré systems can lead to XMR.
• 3D TGS systems exhibit remarkable magnetoresistive properties with potential for spintronic devices.
• Further research into correlated states in 3D moiré systems is warranted.