Universal magnetic proximity effect in ferromagnet-semiconductor quantum well hybrid structures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Hybrid ferromagnet-semiconductor systems exhibit unique properties due to the coupling of magnetic and semiconductor spin systems.
• The long-range magnetic proximity effect extends beyond carrier wave function overlap, mediated by p-d exchange interaction and chiral phonons.
• Understanding this effect is crucial for advancing spintronic device technology.

Purpose of the Study:

• To demonstrate the universality of the long-range magnetic proximity effect in various hybrid structures.
• To investigate the proximity effect in systems using dielectric or semimetal ferromagnets (spinel NiFe2O4, magnetite Fe3O4) and CdTe quantum wells.
• To explore the dynamics of the proximity effect and its potential for device applications.

Main Methods:

• Fabrication of hybrid structures with ferromagnets (Fe3O4, NiFe2O4) and CdTe quantum wells separated by (Cd,Mg)Te barriers.
• Optical characterization using photoluminescence to observe the circular polarization induced by the magnetic proximity effect.
• Analysis of the proximity effect dynamics, including recombination-induced dynamic polarization.

Main Results:

• Demonstrated the universal nature of the long-range magnetic proximity effect across different magnetic materials and barrier compositions.
• Observed proximity effect manifested in photoluminescence circular polarization, originating from the ferromagnet itself.
• Measured an exchange constant (Δexch ≈ 70 μeV) in a magnetite-based structure through dynamic polarization analysis.

Conclusions:

• The long-range magnetic proximity effect is a universal phenomenon in diverse ferromagnet-semiconductor hybrid systems.
• The observed effect, driven by intrinsic magnetic components, offers a pathway for developing novel spintronic devices.
• Electrical control of this interaction holds promise for low-voltage spintronic applications compatible with current electronics.