In particular, the use of PEA-based nanopositioning systems along the sample plane is promising to facilitate the mapping of surfaces of bulk specimens, thin films, and 2D layers such as (beyond-)graphene systems. This improvement is expected to open new perspectives for the characterization of quantum materials. 2,20 Therefore, by introducing a dynamic mode to the static PCAR setup, a lateral degree of freedom in the sample plane is added and makes it possible to map the sample surface. 31,32 Most PCS and PCAR setups reported in the literature 2,20 are static, with the sample kept fixed, while the tip is the only dynamic component. 30 Recent investigations of topological crystalline insulators such as Pb 1− xSn xSe and Pb 1− xSn xTe have pointed at the presence of Majorana fermion-like excitations at the atomic steps of the epitaxial layers. With the emergence of new families of quantum materials encompassing topological insulators, 25 topological crystalline insulators, 26 topological superconductors, 27 Weyl and Dirac semimetals, 28 and unconventional superconductors 29 including heavy fermionic systems, 29 PCS and PCAR have proven to be efficient spectroscopic tools to study these material systems. 16 The recent developments in the fields of STM, 3,4 STS, 16 and, particularly, point contact spectroscopy (PCS), including point contact Andreev reflection (PCAR) spectroscopy, 2,17–24 have underlined the relevance of PEA for nanopositioning applications. 1,9–12Ī major application area for the PEA is represented by scanning probe measurement systems, such as atomic force microscopy (AFM), 13 scanning tunneling microscopy (STM), 3,4,14,15 and scanning tunneling spectroscopy (STS). 8 Despite the limitations imposed by the low working strokes of most commercial PEA stacks, the ones with working strokes ∼(10–30) μm find wide applications in the medical industry, especially in medical implants, scanning fiber endoscopes, lab-on-a-chip for mobile analytics, and nebulizers, in laser technology, in precision mechanical applications and 3D printing, and in the printing industry. Alternative approaches have improved the working strokes of hybrid PEAs to a few centimeters. 1,6,7 The working stroke of a single piezoelectric element is generally limited to a few μm even at room temperature (RT). 1,2 The application of PEA is widespread in basic research fields and in industrial sectors, such as from high resolution scanning probe microscopy (SPM) 3,4 to optical systems for astronomy 5 and the aerospace industry. With the recent development of actuators based on piezoelectric materials, i.e., piezoelectric actuators (PEAs), it is now possible to achieve a spatial resolution of a few nm. The working stroke of an actuator is defined as its linear displacement under dynamic conditions. ![]() 1 The positioning resolution of conventional actuator systems including hydraulic and ac/dc motors is too coarse for most modern technologies, even though these actuators are able to provide large output force and working strokes. The development of precise nanopositioning systems with spatial resolution ∼(1–10) nm and time constant ∼(10–100) μs is relevant for both basic and applied research, as well as for industrial applications. The magnetic field is shown to have no substantial effect on the piezo-properties of the studied piezoelectric-actuator stack. The studied piezoelectric actuator has a maximum displacement of 30 μm at room temperature for a maximum driving voltage of 75 V, which reduces to 1.2 μm with an absolute hysteresis of 9.1 ± 3.3 n m at T = 2 K. Here, the design and realization of an experimental setup based on interferometric techniques to characterize a commercial piezoelectric actuator over a temperature range of 2 K ≤ T ≤ 260 K and magnetic fields up to 6 T are presented. ![]() In particular, the magnitude, the rate, and the associated hysteresis of the piezo-displacement at cryogenic temperatures are the most relevant parameters that determine whether a particular piezoelectric actuator can be used as a nanopositioner. ![]() However, information on the performance of most commercial piezoelectric actuators in cryogenic environment and in the presence of magnetic fields in excess of 5 T is generally not available. Piezoelectric-actuator stacks as nanopositioners with working strokes of 10 μm and positioning resolution ∼(1–10) nm are desirable for both basic research and industrial applications. ![]() The advances in the fields of scanning probe microscopy, scanning tunneling spectroscopy, point contact spectroscopy, and point contact Andreev reflection spectroscopy to study the properties of conventional and quantum materials under cryogenic conditions have prompted the development of nanopositioners and nanoscanners with enhanced spatial resolution.
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