  Materials that have a hysteretic response to an external field are essential
in modern information storage and processing technologies. The magnetization
curves of several natural and artificial materials have previously been
measured and explained in terms of the Neel model, Preisach phenomenological
model, the creation, propagation, and annihilation of topological defects, or
by resonant quantum tunnelling of the magnetization in single molecule magnets.
However, a simple way to design the magnetic response of a material is missing.
Here, we propose and experimentally realize an elementary method to engineer
hysteresis loops in metamaterials built out of dipolar chains. We show that by
tuning the system's interactions and geometry we can induce magnetic responses
with or without remanence at will. Our findings pave the way for the rational
design of hysteretical responses in a variety of physical systems such as
dipolar cold atoms, ferroelectrics, or artificial magnetic lattices, among
others.
