Intrinsic Dynamic Generation of Spin Polarization by Time-Varying Electric Field.

Area of Science:

• Condensed matter physics
• Materials science
• Spintronics

Background:

• Electric control of spin in insulators is crucial for developing low-consumption, ultrafast spintronic devices.
• The underlying mechanisms for dynamic spin generation via electric fields are not well understood.

Purpose of the Study:

• To propose and investigate an intrinsic effect of dynamic spin generation driven by time-varying electric fields in insulators.
• To explore phenomena enabled by this effect, such as linear spin generation and intrinsic Néel spin-orbit torque.

Main Methods:

• Theoretical formulation based on Berry curvature effects in the intraband response regime.
• Analysis of quantum origins in first-order dynamic anomalous spin polarizability.
• First-principles calculations to predict effects in specific materials.

Main Results:

• Identified dynamic spin generation driven by the time derivative of the electric field, distinct from DC effects.
• Predicted linear spin generation in nonmagnetic insulators and intrinsic Néel spin-orbit torque in antiferromagnetic insulators.
• Calculated sizable effects in monolayer Bi and antiferromagnetic MnBi2Te4 under terahertz fields.

Conclusions:

• The proposed intrinsic effect offers a novel pathway for electric control of spin in insulators.
• The predicted phenomena, observable with terahertz fields, open new avenues for spintronic applications.
• This work provides a theoretical framework and experimental targets for dynamic spin control.