Invited Review Article: Microwave spectroscopy based on scanning thermal microscopy: resolution in the nanometer...

Area of Science:

• Physics
• Materials Science
• Nanotechnology

Background:

• Ferromagnetic Resonance (FMR) is a key technique for studying magnetic properties.
• Nanoscale characterization requires high spatial resolution and sensitivity.
• Existing FMR techniques often lack the spatial resolution for single nanostructures.

Purpose of the Study:

• To introduce and detail Scanning Thermal Microscope-detected FMR (SThM-FMR) and Scanning Thermoelastic Microscope-detected FMR (SThEM-FMR).
• To demonstrate the capabilities of SThM/SThEM-FMR for nanoscale magnetic and thermal property analysis.
• To explore the potential of these techniques for advanced materials characterization.

Main Methods:

• SThM-FMR: Combines a thermal near-field microscope with an FMR spectrometer, detecting thermal response via resistivity changes.
• SThEM-FMR: Utilizes a similar setup but detects the thermoelastic response for localized FMR spectra.
• Both techniques employ nanoprobe detection for high spatial resolution.

Main Results:

• SThM-FMR achieves 1 mK temperature resolution and 30 nm local resolution.
• SThEM-FMR provides 10 nm local resolution, ideal for single nanostructures.
• Detection limits down to 10^6 spins are achievable with both methods.
• Investigations revealed local magnetic anisotropies, magnetization dynamics, and finite-size effects.

Conclusions:

• SThM/SThEM-FMR are powerful techniques for nanoscale magnetic and thermal characterization.
• These methods provide simultaneous information on magnetic, topographic, and thermal properties.
• Future applications include combined magnetoresistance and FMR studies for advanced materials.