  We use molecular dynamics simulations of a simple model to show that
dispersions of slightly elongated colloidal particles with long-range dipolar
interactions, like ferrofluids, can form a physical (reversible) gel at low
volume fractions. On cooling, the particles first self-assemble into a
transient percolating network of cross-linked chains, which, at much lower
temperatures, then undergoes a kinetic transition to a dynamically arrested
state with broken ergodicity. This transition from a transient to a frozen gel
is characterised by dynamical signatures reminiscent of jamming in much denser
dispersions.
