A modular point contact spectroscopy probe for sub-Kelvin applications

Abstract

We present the construction and performance of a plug-n-play type point contact spectroscopy probe equipped with a piezo-driven coarse approach mechanism for sub-kelvin applications. A modular assembly has been built which can be placed in or taken out from a sub-Kelvin socket mounted inside a He3 cryostat (with a 7 Tesla magnet) using an external manipulator. A simple transfer process using a removable vertical manipulator combined with a load-lock chamber makes the exchange of the sample/tip rig very easy without breaking the vacuum insulation of the sample chamber. We have successfully performed point-contact spectroscopic studies on few elemental superconductors with low Tc. We have also used the probe to perform spectroscopic measurements on another low temperature superconductor PdTe2, which is a Dirac semimetal in the normal state. We present such data to demonstrate the functionality of the probe. The probe can also be made adaptable for other transport measurements such as Hall effect, four probe resistivity, scanning tunnelling spectroscopy etc.

The pressure-enhanced superconducting phase of Sr$$_x$$–Bi$$_2$$Se$$_3$$ probed by hard point contact spectroscopy

“…Here our aim was to probe the pressure-induced re-entrant, enhanced superconducting phase of Sr–Bi Se . For that we used a home-built point contact spectroscopy set up working down to 400 mK 29 in another cryostat. First a silver (Ag) tip was engaged gently on the surface of the crystal thus forming mesoscopic point contact junctions between Ag and Sr–Bi Se .…”

Applications of point-contact spectroscopy in the study of topological materials

“…Giaever [12] 针尖的逼近精度是通过精密差分螺旋 [1] 或更加精密的 压电双晶梁 [1] 、压电陶瓷驱动的精密位移台 [17,18] 等装 置来实现的. 此类装置的缺点是机械稳定性不易控制,…”

Low temperature and high magnetic field performance of a commercial piezo-actuator probed via laser interferometry

“…With the recent development of actuators based on piezoelectric materials i.e. piezoelectric-actuator (PEA), it is now possible to achieve spatial resolution of a few nm 1,2 . The application of PEA is wide spread in basic research fields and in industrial sectors, from high resolution scanning probe microscopy (SPM) 3,4 , to optical systems for astronomy 5 and aerospace industry 1,6,7 .…”

“…A major application area for the PEA is represented by scanning probe measurement systems such as atomic force microscopy (AFM) 9 , scanning tunneling microscopy (STM) 3,4,10,11 , and scanning tunneling spectroscopy (STS) 12 . The recent developments in the fields of STM 3,4 , STS 12 and in particular of point contact spectroscopy (PCS) including point contact Andreev reflection spectroscopy (PCAR) 2,[13][14][15][16][17][18][19][20] , have underlined the relevance of PEA for nanopositioning applications. With the emergence of new families of quantum materials encompassing topological insulators 21 , topological crystalline insulators 22 , topological superconductors 23 , Weyl and Dirac semimetals 24 and unconventional superconductors 25 including heavy fermionic systems 25 , PCS and PCAR have proven to be efficient spectroscopic tools to study these material systems 26 .…”