Implementation of radio-frequency magnetic fields for electron spin resonance in a low-temperature atomic force...

Area of Science:

• Quantum control
• Surface science
• Nanotechnology

Background:

• Electron spin resonance in scanning tunneling microscopy (ESR-STM) allows atomic-scale spin system control.
• Current ESR-STM methods indirectly use RF electric fields to generate effective RF magnetic fields.
• A direct RF magnetic field generation is needed when field conversion is not feasible.

Purpose of the Study:

• To develop and implement a direct low-gigahertz radio-frequency (RF) magnetic field generation for scanning probe microscopy.
• To enable electron spin resonance (ESR) applications where RF electric field conversion is not viable.

Main Methods:

• Designed and utilized a single-loop coil on a flexible polyimide printed-circuit-board to generate RF magnetic fields.
• Employed a gold-microstrip on an insulating support as a sample surface to locally enhance the RF magnetic field.
• Tested the system's performance up to 3 GHz.

Main Results:

• Successfully generated a low-GHz RF magnetic field in a scanning probe setup.
• Observed moderate frequency dependence and no sharp resonances in transmission up to 3 GHz.
• Demonstrated the capability of this method for ESR in atomic force microscopy (AFM) on individual pentacene molecules.

Conclusions:

• The developed RF magnetic field generation is a significant advancement for ESR-STM and related techniques.
• This method overcomes limitations of indirect field generation, expanding the scope of ESR applications at the atomic scale.
• The successful demonstration on pentacene molecules highlights the potential for studying spin phenomena in individual molecules.