  Metastable self-organized electronic states in quantum materials are of
fundamental importance, displaying emergent dynamical properties that may be
used in new generations of sensors and memory devices. Such states are
typically formed through phase transitions under non-equilibrium conditions and
the final state is reached through processes that span a large range of
timescales. By using time-resolved optical techniques and
femtosecond-pulse-excited scanning tunneling microscopy (STM), the evolution of
the metastable states in the quasi-two-dimensional dichalcogenide 1T-TaS2 is
mapped out on a temporal phase diagram using the photon density and temperature
as control parameters on timescales ranging from 10^(-12) to 10^3 s. The
introduction of a time-domain axis in the phase diagram enables us to follow
the evolution of metastable emergent states created by different phase
transition mechanisms on different timescales, thus enabling comparison with
theoretical predictions of the phase diagram and opening the way to
understanding of the complex ordering processes in metastable materials.

Strongly Correlated Electrons