Atomic and Molecular Layer Deposition of Chiral Thin Films Showing up to 99% Spin Selective Transport

Abstract

Spin electronics is delivering a much desired combination of properties such as high speed, low power, and high device densities for the next generation of memory devices. Utilizing chiral-induced spin selectivity (CISS) effect is a promising path toward efficient and simple spintronic devices. To be compatible with state-of-the-art integrated circuits manufacturing methodologies, vapor phase methodologies for deposition of spin filtering layers are needed. Here, we present vapor phase deposition of hybrid organic–inorganic thin films with embedded chirality. The deposition scheme relies on a combination of atomic and molecular layer deposition (A/MLD) utilizing enantiomeric pure alaninol molecular precursors combined with trimethyl aluminum (TMA) and water. The A/MLD deposition method deliver highly conformal thin films allowing the fabrication of several types of nanometric scale spintronic devices. The devices showed high spin polarization (close to 100%) for 5 nm thick spin filter layer deposited by A/MLD. The procedure is compatible with common device processing methodologies.

Transverse magnetoconductance in two-terminal chiral spin-selective devices

“…17,18 Some experimental work shows zero CISS signal at low bias, 7 whereas some other experiments appear to report non-zero CISS effect in this range, and hence apparent violation of the Onsager reciprocity condition. 8,10,11…”

Sensitive Chirality Measurements with Electrical Readout Utilizing the CISS Effect

“…In this case, the nanometric active area is with a wide response spectrum and the electro-optical activation allows direct measurement of the CD spectrum of chiral species with electrical readout. [15,16] The device is local and fast and relies on a plasmonic antenna coupled to an external electrical readout. Illumination of the device with circularly polarized light provides a direct measurement of the enantiopurity of very small sample quantities, down to 100 molecules.…”

“…Nanofloret CISS device with a nanometric junction – that can measure a more accurate and local electro‐optical signal. In this case, the nanometric active area is with a wide response spectrum and the electro‐optical activation allows direct measurement of the CD spectrum of chiral species with electrical readout [15,16] . The device is local and fast and relies on a plasmonic antenna coupled to an external electrical readout.…”

Combined Atomic and Molecular Layer Deposition Surface Modification of Carbon Nanotubes for CNT–Epoxy Polymer Composites

“…The interphase layer thickness deposited is obtained with Angstrom-level precision, typical to atomic and molecular layer deposition methodologies. 8 Furthermore, while covalent functionalization typically requires strong acids and/or other oxidants, 9 noncovalent functionalization offers low cost, simple implementation, and lower environmental impact by avoiding the need for strong acids and/or oxidizing agents. 10 Polymer wrapping, surfactant adsorption, and other methods such as endohedral incorporation were practiced earlier, as mentioned in the literature, to implement noncovalent functionalization of CNTs.…”

“…As the CNTs are processed in the gas phase, a uniform layer is deposited by gas phase diffusion of the reactants. The interphase layer thickness deposited is obtained with Angstrom-level precision, typical to atomic and molecular layer deposition methodologies …”