Design and construction of a point-contact spectroscopy rig with lateral scanning capability

Abstract

The design and realization of a cryogenic rig for point-contact spectroscopy measurements in the needle-anvil configuration is presented. Thanks to the use of two piezoelectric nano-positioners, the tip can move along the vertical (z) and horizontal (x) direction and thus the rig is suitable to probe different regions of a sample in situ. Moreover, it can also form double point-contacts on different facets of a single crystal for achieving, e.g., an interferometer configuration for phase-sensitive measurements. For the later purpose, the sample holder can also host a Helmholtz coil for applying a small transverse magnetic field to the junction. A semi-rigid coaxial cable can be easily added for studying the behavior of Josephson junctions under microwave irradiation. The rig can be detached from the probe and thus used with different cryostats. The performance of this new probe has been tested in a Quantum Design PPMS system by conducting point-contact Andreev reflection measurements on Nb thin films over large areas as a function of temperature and magnetic field.

Hybridization gap in the heavy-fermion compound UPd2Al3 via quasiparticle scattering spectroscopy

“…Immediately after the ion beam etching, the sample holder was quickly attached to the PCS rig, typically within a few minutes and subsequently inserted into a cryostat (Quantum Design, PPMS DynaCool). In this study, we focus only upon the non-superconducting state, so all of the presented data were taken between 4 K and 25 K. Ballistic metallic junctions were formed in situ at low temperature using an electrochemically polished gold tip [26] mounted on a homemade PCS rig with piezo-driven nano-positioners [27]. The differential conductance of a junction, G(V) = dI/dV, was measured with a standard four-probe lock-in technique as a function of temperature and applied magnetic field.…”

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,…”

A modular point contact spectroscopy probe for sub-Kelvin applications

“…A measurement probe for a He4 cooled system, which goes down to 1.4 K 4,26 and where exchange gas plays an important role to cool down the sample space, is quite easy to fabricate and handle. However, designing a probe for a He3 system, which goes down to sub-Kelvin temperature is a quite a challenging job as the sample probe needs to be transferred into a chamber maintained at high vacuum.…”