Manipulating surface-related ferromagnetism in modulation-doped topological insulators

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Topological insulators (TI) possess unique surface states protected by time-reversal symmetry (TRS).
• Introducing ferromagnetism to TIs can lead to exotic phenomena and potential device applications.
• Engineering heterostructures is crucial for controlling TI properties.

Purpose of the Study:

• To investigate the magnetic responses in magnetically modulation-doped TI bilayer films.
• To explore the electrical tunability of surface ferromagnetism in TI heterostructures.
• To understand the influence of magnetic interaction range on surface magneto-electric effects.

Main Methods:

• Fabrication of (Bi(z)Sb(1-z))2Te3/Cr(x)(Bi(y)Sb(1-y))2Te3 bilayer films.
• Magnetic modulation doping of TI heterostructures.
• Electrical tuning of the Fermi level across the Dirac point.
• Characterization of magnetic responses and surface carrier mediation.

Main Results:

• Demonstrated that TI surface carriers mediate magnetic impurities, generating robust ferromagnetic order.
• Showed that surface magneto-electric effects can be enhanced or suppressed by controlling magnetic interaction range.
• Achieved electrical manipulation of surface-related ferromagnetism in modulation-doped TI devices.

Conclusions:

• The study highlights the potential of TI heterostructures for realizing TRS-breaking topological physics.
• Electrical control over surface ferromagnetism in TIs opens avenues for multifunctional spintronic devices.
• This work advances the understanding and application of topological insulator-based multifunctional heterostructures.