Memory effect in a topological surface state of Bi2Te2Se

Area of Science:

• Condensed Matter Physics
• Materials Science
• Surface Science

Background:

• Topological insulators possess unique surface states with potential for novel electronic applications.
• Controlling these surface states locally is crucial for device fabrication.
• Bi2Te2Se offers a promising platform due to its suppressed bulk carrier density.

Purpose of the Study:

• To demonstrate controllable local manipulation of the Dirac surface state in Bi2Te2Se.
• To investigate the influence of bias voltage and magnetic fields on surface state properties.
• To elucidate the mechanism behind observed memory effects.

Main Methods:

• Utilizing scanning tunneling microscopy/spectroscopy (STM/S) under applied magnetic fields.
• Analyzing Landau levels in conductance spectra to probe the Dirac surface state.
• Performing controlled bias voltage ramping and imaging.

Main Results:

• Observed Landau levels of the Dirac surface state in conductance spectra.
• Demonstrated bias voltage-dependent energy shifts and hysteresis in conductance spectra, indicating a memory effect.
• Revealed spatially inhomogeneous conductance patterns controllable by bias voltage.

Conclusions:

• The observed memory effect is attributed to tip-induced local charging pinned by defect potentials.
• This work establishes a new method for the controllable manipulation of topological surface states.
• The findings pave the way for novel electronic devices based on topological insulators.