Spectroscopy and microscopy of spin-sensitive rectification current induced by microwave radiation

Area of Science:

• Surface Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Scanning tunneling microscopy (STM) is a powerful tool for surface analysis.
• Nonlinear electrical properties of STM junctions can be exploited for novel measurements.
• Spin-dependent transport is crucial for understanding magnetism at the nanoscale.

Purpose of the Study:

• To investigate the rectification of tunneling current induced by amplitude-modulated microwave radiation in an STM junction.
• To demonstrate the spin-sensitivity of this microwave-induced rectification.
• To utilize this technique for probing magnetic properties of surfaces and tip materials.

Main Methods:

• Application of amplitude-modulated microwave radiation to an STM junction.
• Measurement of the rectified tunneling current, which is proportional to the second derivative of the current-voltage characteristic (d(2)I/dV(2)).
• Manipulation of the magnetic domain at the apex of an iron-coated STM tip using an external magnetic field.
• Measurement of spin-dependent current changes through a Cr(001) surface to detect spin flip and magnetic hysteresis.

Main Results:

• Microwave radiation induces a measurable rectification current in the STM junction due to its nonlinearity.
• The rectification current exhibits a direct proportionality to the d(2)I/dV(2) signal, indicating its sensitivity to electronic properties.
• The technique successfully detected spin-dependent current changes, enabling the measurement of spin flip moments and magnetic hysteresis of the tip's magnetic domain.

Conclusions:

• Microwave-induced current rectification in STM junctions is a viable method for probing spin-dependent electronic properties.
• This technique offers a novel approach to manipulate and measure magnetic domains with high sensitivity.
• The findings pave the way for advanced spintronic applications using STM.