https://phys.org/news/2018-05-antiferromagnetic-materials-terahertz.html

But this is not the case with antiferromagnetic memory, which can be written at a much higher density because the bar magnets are always aligned alternately, and so have no effect on each other. This means they can store considerably more data and allow much faster writing speeds.

Antiferromagnetic memory allows for terahertz processing rates