Intrinsic Organic‐Based Synthetic/Artificial Antiferromagnets

Abstract

Mn(TCNE)[C4(CN)8]1/2 (TCNE = tetracyanoethylene) and [NEt4]Mn(II)3(CN)7 have extended layers with nearest neighbor intralayer S = 5/2 and S = 1/2 spin sites that couple antiferromagnetically forming ferrimagnetic layers. These layers are uniformly connected via diamagnetic (nonmagnetic) bridging μ4-[(C4(CN)8](2-) (8.77 Å) or μ-CN (5.48 Å) ligands, respectively, that antiferromagnetic couple the ferrimagnetic layers resulting in an antiferromagnet. The Jinter/kB is -1.0 and -1.8 K (H=-JSi⋅Sj) for Mn(TCNE)[C4(CN)8]1/2 and [NEt4]Mn(II)3(CN)7, respectively. Albeit intrinsically multilayered, these antiferromagnets have the same motif as that for artificial/synthetic antiferromagnets that exhibit giant magnetoresistance (GMR) and are commercially used in many magnetic memory applications.

Anomalous Stoichiometry, 3-D Bridged Triangular/Pentagonal Layered Structured Artificial Antiferromagnet for the Prussian Blue Analogue A3MnII5(CN)13(A = NMe4, NEtMe3). A Cation Adaptive Structure

“…Each layer is ferrimagnetic due to the antiferromagnetic coupling between adjacent high- ( S = 5/2) and low-spin ( S = 1/2) Mn II sites, as occurs for antiferromagnet [NEt 4 ]­Mn II 3 (CN) 7 and ferrimagnet [NEt 4 ] 2 Mn II 3 (CN) 8 . Hence, A 3 Mn 5 (CN) 13 (A = NMe 4 , NEtMe 3 ) are rare examples of intrinsic artificial antiferromagnets (AAF), which are increasingly important for the development of spin valves (albeit using extrinsic, deposition-prepared AAFs) . These materials along with M­(TCNE)­[C 4 (CN) 8 ] 1/2 (M = Mn, Fe) are the first intrinsic, chemically prepared, and controlled AAFs and have the advantage of having controlled uniform spacing between the layers as they are not physically prepared via deposition methods.…”

Stimuli responsive furan and thiophene substituted difluoroboron β-diketonate materials

“…14 Exciton migration to lower energy emitting H-aggregates in the amorphous state is believed to be responsible for the red-shift in fluorescence observed upon smearing. 20 Substituents attached to the bdk ligand, such as halides 7,21 or alkoxyl chains of varying length, 6 are also known to affect ML properties. Aryl substituted BF 2 bdks with donor-acceptor motifs typically exhibit high-contrast, reversible ML.…”

Magnets for this Millennium Based Upon Coordination Compounds and New Coordination Chemistry

“…30 (NEt 4 )Mn II 3 (CN) 7 is an artificial antiferromagnet as the antiferromagnetic coupling occurs through the non-magnetic cyanides lying between the adjacent magnetic layers as occurs for giant magnetoresistance etc. [31][32][33] Fig. 8 𝜒T(T) (•) and 𝜒 -1 (T) (o) for the artificial antiferromagnet (NEt 4 )Mn II 3 (CN) 7 .…”

“…Thus, like (NEt 4 )Mn II 3 (CN) 7 and A 3 Mn II 5 (CN) 13 , Mn II (TCNE)[C 4 (CN) 8 ] 1/2 is also an artificial antiferromagnet as antiferromagnetic coupling of the ferrimagnetic layers occurs via the non-magnetic -N ≡ CCC ≡ N-moiety that bridges the adjacent ferrimagnetic layers. [31][32][33] Fig. 24 χ'(T) (•) and χ''(T) (o) for Mn II (TCNE)[C 4 (CN) 8 ] 1/2 .…”