Characterization of spin crossover crystal surface by AFM

Imaging nano‐domains in spin crossover (SCO) compounds remains so far an unreached goal. We report on the first AFM tapping‐mode investigation of SCO single crystals, performed at room temperature with the well known mononuclear compound [Fe(ptz) 6 ](BF 4 ) 2 (ptz = 1‐propyl‐tetrazole) and the trinuclear supramolecular compound [Fe 3 (hyetrz) 6 (H 2 O) 6 ](CF 3 SO 3 ) 6 (hyetrz = 4‐(2′‐hydroxyethyl)‐1,2,4‐triazole) which shows a gradual spin conversion centred at room temperature. The natural surface of the former crystal revealed a volatile coating of the scanned area attributed to the transport of adsorbed water under the effect of interaction with the AFM tip. The second one showed astonishing leopard‐skin patterns assigned to the effect of atmospheric humidity on this hygroscopic compound. Their origin is discussed. We suggest the use of fluid coating layers as a general method for revealing the nano‐patterning of physical properties ( e.g. like‐spin domains) at the surface of dielectric materials. AFM‐tapping images of [Fe 3 (hyetrz) 6 (H 2 O) 6 ](CF 3 SO 3 ) 6 at room temperature and ambient atmosphere. magnified image