Piezoelectric materials have many applications at cryogenic temperatur
es. However, the piezoelectric response below 10 kelvin is diminished,
making the use of these materials somewhat marginal. Results are pres
ented on strontium titanate (SrTiO3), which exhibits a rapidly increas
ing piezoelectric response with decreasing 'temperature below 50 kelvi
n; the magnitude of its response around 1 kelvin is comparable to that
of the best materials at room temperature. This ''giant'' piezoelectr
ic response may open the way for a broad class of applications includi
ng use in ultralow-temperature scanning microscopies and in a magnetic
field-insensitive thermometer. These observations, and the possible d
ivergence of the mechanical response to electric fields at even lower
temperatures, may arise from an apparent quantum critical point at abs
olute zero.