A top-loading point-contact spectroscopy probe with in-situ sample exchange for dilution refrigerators

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spectroscopy

Background:

• Advanced spectroscopic techniques are crucial for understanding quantum materials.
• Investigating superconductivity at millikelvin temperatures requires specialized instrumentation.

Purpose of the Study:

• To design and implement a point-contact spectroscopy system integrated with a dilution refrigerator.
• To enable reliable spectroscopic measurements at ultra-low temperatures (down to 30 mK).

Main Methods:

• Utilized a needle-anvil geometry with a cryogenic piezo-driven nanopositioner for mesoscopic point contact formation.
• Implemented advanced thermal anchoring strategies for efficient cooling and stable operation.
• Performed point-contact spectroscopy on Ta-doped TiSe2 and niobium.

Main Results:

• Successfully achieved stable measurements at 30 mK.
• Demonstrated the system's capability by observing well-defined superconducting features in TaxTi1-xSe2 and niobium.
• Observed systematic diminishment of superconducting features with increasing temperature and magnetic field.

Conclusions:

• The developed point-contact spectroscopy system is a robust and versatile tool for millikelvin-temperature research.
• The platform facilitates spectroscopic investigations of superconductors and other quantum materials.
• The system is suitable for high magnetic field applications in condensed matter physics.