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

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 at cryogenic conditions have prompted the development of nanopositioners and nanoscanners with enhanced spatial resolution. Piezoelectric-actuator stacks as nanopositioners with working strokes $>100~\mu\mathrm{m}$ and positioning resolution $\sim$(1-10) nm are desirable for both basic research and industrial applications. 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. In particular, the magnitude, 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. Here, the design and realization of an experimental set-up based on interferometric techniques to characterize a commercial piezoelectric-actuator over a temperature range of $2~\mathrm{K}\leq{T}\leq260~\mathrm{K}$ and magnetic fields up to 6\,T is presented. The studied piezoelectric-actuator has a maximum displacement of $30~\mu\mathrm{m}$ at room temperature for a maximum driving voltage of 75\,V, which reduces to $1.2~\mu\mathrm{m}$ with an absolute hysteresis of $\left(9.1\pm3.3\right)~\mathrm{nm}$ at $T=2\,\mathrm{K}$. The magnetic field is shown to have no substantial effect on the piezo properties of the studied piezoelectric-actuator stack.