Extended Data Fig. 6 | a.c. magnetic susceptibility data. a, b, In-phase (a) and
out-of-phase (b) variable-temperature a.c. magnetic susceptibility data from 2
to 10 K for 1 (FeCl 2 ) 19 under zero d.c. magnetic field and a 0.4 mT a.c. magnetic
field oscillating at frequencies of 1, 5, 7.5, 10, 50, 75, 100, 500, 750 and 1,000 Hz
(blue to red). Coloured lines are guides for the eye.