  The speed of writing of state-of-the-art ferromagnetic memories is physically
limited by an intrinsic GHz threshold. Recently, an alternative research
direction has been initiated by realizing memory devices based on
antiferromagnets in which spin directions periodically alternate from one
atomic lattice site to the next. In our work we experimentally demonstrate at
room temperature that the speed of reversible electrical writing in a memory
device can be scaled up to THz using an antiferromagnet. Efficient
current-induced spin-torque mechanism is responsible for the switching in our
memory devices throughout the twelve orders of magnitude range of writing
speeds from Hz to THz. Our work opens the path towards the development of
memory-logic technology reaching the elusive THz band.
