A high-spin organic diradical as a spin filter

Abstract

Here, in this work we have designed a molecular bridge structure which can be used as a spin filter where the prototypical highly ferromagnetic m-phenylene connected bis(aminoxyl) diradical is used as a bridging fragment between two semi-infinitely widened gold (Au) electrodes along the [100] direction. A state-of-the-art non-equilibrium Green function's (NEGF) method coupled with the density functional theory (DFT) was carried out on this two-probe molecular bridge system to understand its electrical spin transport characteristics. The spin current at various bias voltages from 0.00 V to 4.00 V at intervals of 0.20 V for this Au-diradical-Au molecular junction is evaluated. We also quantify the bias-dependent spin injection coefficients (BDSIC) at different bias voltages and also the spin-filter efficiency at equilibrium, i.e., at zero bias voltage. Also plots of BDSIC vs. voltage, the up- and down-spin current vs. voltage (I-V) curves, and density of states (DOS) at zero bias voltage are evaluated.

Stable Organic (Bi)Radicals by Delocalization of Spin Density into the Electron‐Poor Chromophore Core of Isoindigo

“…Since the discovery of the first biradicaloid polycyclic aromatic hydrocarbon (PAH) by Tschitschibabin in 1907, the interest in organic open shell π‐conjugated compounds has increased tremendously due to their unique optical, electronic and magnetic properties . Usually, open‐shell PAHs exhibit redox amphoterism, comparatively small HOMO–LUMO energy gaps, enhanced second hyperpolarizability and large two‐photon absorption cross‐sections which makes them interesting for the development of new ambipolar field‐effect transistors, second generation solar cells based on singlet fission, non‐linear optics, energy storage or electronic devices as well as for organic spintronics . Generally, the degree of biradical character y can range from zero (completely closed‐shell) to one (completely open‐shell) with overall spin angular momenta of S= 0 for singlet and S= 1 for triplet states which can be predicted by applying Ovchinnikov's parity model .…”

Preparation of Multi‐Spin Systems: A Case Study of Tolane‐Bridged Verdazyl‐Based Hetero‐Diradicals

“…The purely organic high‐spin systems based on nitroxides, verdazyls, trityls, and phenoxides are widely applied as labels for structural studies of biological objects with the EPR technique, as agents for dynamic nuclear polarisation, and as potential components of a quantum computer Furthermore, such high‐spin paramagnets have been used for the tuning of magneto‐optic properties of a chiral polymer and fabrication of electronic devices, e.g., as electrochemical switchers and memory devices, hole‐transporting materials, and spin filters …”

Close relation between quantum interference in molecular conductance and diradical existence

“…Herrmann and coworkers (17,18) have explored the relationship between molecular conductance and magnetic coupling, but also its limit. Very recently, Klein and coworkers have found that a high-spin π-diradical can play an important role in molecular junctions as a spin filter (50).…”