Feedback lock-in: A versatile multi-terminal measurement system for electrical transport devices

Area of Science:

• Materials Science
• Electrical Engineering
• Condensed Matter Physics

Background:

• Accurate measurement of small currents and voltages is crucial for characterizing multi-terminal electronic devices.
• Traditional methods often require complex setups and lack flexibility for dynamic configuration switching.

Purpose of the Study:

• To design and implement a versatile measurement system for parallel electrical characterization.
• To enable software-controlled dynamic configuration of measurement probes.
• To achieve high-sensitivity measurements without specialized current preamplifiers.

Main Methods:

• Development of a feedback lock-in system integrating digital feedback control and software-defined lock-in measurements.
• Utilizing commercially available digital I/O boards, custom voltage preamplifiers, and open-source software.
• Software control of probe input impedance to function as voltage or current leads.

Main Results:

• Demonstrated differential measurement sensitivity comparable to commercial lock-in amplifiers.
• Successfully performed efficient multi-terminal electrical transport measurements on twisted bilayer graphene and SrTiO3 quantum point contacts.
• Enabled a novel measurement approach using multiple current probes on a ballistic graphene device.

Conclusions:

• The feedback lock-in system offers a flexible and sensitive platform for advanced electrical characterization.
• The system's adaptability facilitates efficient measurements on complex quantum materials.
• The developed technology opens avenues for new experimental methodologies in electronic transport studies.