  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.
