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First Step Towards a Devil's Staircase in Spin‐Crossover Materials
Author(s) -
Trzop Elzbieta,
Zhang Daopeng,
PiñeiroLopez Lucia,
ValverdeMuñoz Francisco J.,
Carmen Muñoz M.,
Palatinus Lukas,
Guerin Laurent,
Cailleau Hervé,
Real Jose Antonio,
Collet Eric
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201602441
Subject(s) - spin crossover , aperiodic graph , bimetallic strip , bistability , superspace , crystallography , lattice (music) , spin states , chemistry , sequence (biology) , spin (aerodynamics) , condensed matter physics , physics , thermodynamics , combinatorics , quantum mechanics , mathematics , biochemistry , organic chemistry , supersymmetry , acoustics , metal
The unprecedented bimetallic 2D coordination polymer {Fe[(Hg(SCN) 3 ) 2 ](4,4′‐bipy) 2 } n exhibits a thermal high‐spin (HS)↔low‐spin (LS) staircase‐like conversion characterized by a multi‐step dependence of the HS molar fraction γ HS . Between the fully HS ( γ HS =1) and LS ( γ HS =0) phases, two steps associated with different ordering appear in terms of spin‐state concentration waves (SSCW). On the γ HS ≈0.5 step, a periodic SSCW forms with a HS‐LS‐HS‐LS sequence. On the γ HS ≈0.34 step, the 4D superspace crystallography structural refinement reveals an aperiodic SSCW, with a HS‐LS sequence incommensurate with the molecular lattice. The formation of these different long‐range spatially ordered structures of LS and HS states during the multi‐step spin‐crossover is discussed within the framework of “Devil's staircase”‐type transitions. Spatially modulated phases are known in various types of materials but are uniquely related to molecular HS/LS bistability in this case.