Organic Radicals As Spin Filters

Abstract

Molecular spintronics has received extensive interest in recent years. Due to their favorable properties such as long spin coherence lengths and an amenability to fine-tuning via chemical substituents, organic materials play a prominent role in this field. Here we discuss how organic radicals may act as spin filters in the coherent tunneling regime and how they may be tuned to filter either majority- or minority-spin electrons by adding electron-donating or -withdrawing substituents. For a set of benzene-based model systems, we identify dips in the spin-resolved transmission, which may be caused by destructive interference, as a desirable feature when aiming for efficient spin filtering. Furthermore, the qualitative predictions made for our model systems are shown to be transferable to larger stable radicals.

Robust Manipulation of Magnetism in Dilute Magnetic Semiconductor (Ga,Mn)As by Organic Molecules

“…[ 16,17 ] The ferromagnetic-organic interface, as an essential component of molecular spintronic devices, has been the focus of many recent studies [ 18,19 ] due to the prospects of producing novel electrical and magnetic functionalities. So far, studies of molecular modifi cation of magnetism have mostly focused on metals where the effects are limited to the surface because of the large carrier densities and short screening lengths: [ 17,20 ] Both theoretical calculations [ 19,21 ] and experiments [ 15,16,19 ] have revealed possible presence of large spin polarization and spin-fi ltering effect at the interface of nonmagnetic organic molecules and …”

Control of Magnetism in Dilute Magnetic Semiconductor (Ga,Mn)As Films by Surface Decoration of Molecules

“…For instance, the ferromagnet-molecule interface has been the focus of many recent studies [43,44], due to their novel electrical and magnetic functionalities. Spinfiltering effect and large spin polarization at the interface of ferromagnetic metals and nonmagnetic organic molecules have been revealed both by theoretical calculations [44,45] and experiments [44,46,47]. Interfacial magnetization in the organic molecules may also be induced [48] and the surface magnetic anisotropy of the ferromagnetic metal be modified [49].…”

Spin in density‐functional theory

“…In fact, the electronic spin gives rise to a magnetic moment that makes such molecular systems functional for various purposes. For instance, organic radicals can be used as spin probes in biomolecules [1] and are of interest as building blocks for molecular spintronics devices, [2,3] single-molecule magnets have the potential to act as molecular qubits for quantum information processing, [4] and open-shell transition metal compounds serve as catalytic centers in (bio-)inorganic chemistry, [5][6][7][8] where a change in the spin state can be an essential step in the catalytic cycle. [9] Consequently, a first-principles theory that is useful for descriptive and analytic purposes and that has the potential to be a predictive tool in theoretical studies on such chemical systems must consider the spin properties of the electronic structure.…”