Mechanisms for Strong Anisotropy of In-Plane g-Factors in Hole Based Quantum Point Contacts

Area of Science:

• Condensed matter physics
• Semiconductor spintronics
• Quantum transport phenomena

Background:

• In-plane hole g factors in quantum point contacts (QPCs) exhibit strong magnetic field orientation dependence relative to electric current.
• This anisotropic behavior, observed for a decade, remains a significant unresolved issue in semiconductor physics.

Purpose of the Study:

• To systematically investigate the mechanisms causing the observed anisotropy in hole g factors.
• To develop a theoretical framework that successfully explains this magnetic field dependence in p-type heterostructures.

Main Methods:

• Experimental measurements of in-plane hole g factors in p-type heterostructure-based QPCs.
• Theoretical modeling to analyze and attribute the observed anisotropic effects.

Main Results:

• Identified a novel anisotropy mechanism involving an additional B_{+}k_{-}^{4}σ_{+} effective Zeeman interaction for holes.
• Demonstrated that this new interaction is kinematically distinct from the previously considered B_{-}k_{-}^{2}σ_{+} Zeeman term.
• Provided a successful theoretical description for the experimentally observed g factor anisotropy.

Conclusions:

• The B_{+}k_{-}^{4}σ_{+} Zeeman interaction is a key factor in understanding anisotropic hole g factors in QPCs.
• This finding resolves a long-standing problem in the field of spintronics.
• The developed theory offers a more complete picture of spin interactions in low-dimensional semiconductor systems.