Tuneability and criticality in a three-dimensional stacked molecular system

Abstract

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Magnetic ordering of defects in a molecular spin-Peierls system

“…redSince µSR is an excellent probe of weak, local magnetic fields it presents some significant advantages for studying the static and dynamic properties of the defect states.The sensitivity of this technique is a consequence of the fact that muons can implant close to local magnetic moments and experience their local dipolar magnetic fields. The high temperature behaviour through T SP of the muon relaxation has been previously studied [27] and so here, we only focus on the low temperature behaviour. The relaxation at low temperatures is complex as there are many different relaxation mechanisms but at short times one is able to resolve a heavily damped oscillation, a signature of static magnetic moments, on a strongly relaxing background.…”

“…Furthermore, this transition can be tuned by replacing protons with fluorine atoms on the quinoidal ring of TCNQ using TCNQF 4 (TCNQF 4 = 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) where a shift in T SP to 160 K is observed [27]. TCNQF 4 is a stronger acceptor than TCNQ as the F atoms can draw an increased amount of electron density into the quinoidal structure.…”

The low energy phonon modes of the hydrogenated and deuterated π-conjugated system 7,7,8,8-tetracyanoquinodimethane: an inelastic neutron scattering study

“…TCNQ was shown to not only conduct electricity but also able to stablise a radical anion creating an S = 1/2 system that showed interesting magnetic properties. This discovery led to a deluge of research that focused on the novel properties of different compounds [5][6][7][8][9][10][11][12][13] . Substituted TCNQ-based quinodial structures have also shown some interesting optical properties as researchers began to explore cyano-chemistry, most notably mono-substituted TCNQ molecules forming highly polarisable non-linear optical materials 14,15 .…”

“…Simple TCNQ based salts such as K + TCNQ − as well as other alkali metal salts form 1D magnetic systems that exhibit spin-Peierls transitions due to the 1D interactions along these 1D TCNQ anion stacks [17][18][19] . However, recent work has shown that dynamically, this transition is actually 3D and there must be strong coupling of the 1D magnetism with the 3D structural transition 11 . In recent years, TCNQ based compounds have also been shown to exhibit the characteristics of functional materials.…”

A collapse of ferromagnetism in an organic based magnet under pressure

“…TCNQ is a flat, planer molecule that forms many compounds where interactions along the 1D π-stacked structure can play important/dominant roles, such as is observed with metalinsulator, Peierls and spin-Peierls transitions (SP) [3,4,5,6,7]. In the case of [Fe(III)Cp][TCNQ], both polymorphs show an increase in the magnetic transition as a function of pressure due to increased coupling as intra-and inter-chain distances decrease [8].…”