How spin relaxes and dephases in bulk halide perovskites.

Spintronics in halide perovskites has drawn significant attention in recent years, due to their highly tunable spin-orbit fields and intriguing interplay with lattice symmetry. Here, we perform first-principles calculations to determine the spin relaxation time (T1) and ensemble spin dephasing time ([Formula: see text]) in a prototype halide perovskite, CsPbBr3. To accurately capture spin dephasing in external magnetic fields we determine the Landé g-factor from first principles and take it into account in our calculations. These allow us to predict intrinsic spin lifetimes as an upper bound for experiments, identify the dominant spin relaxation pathways, and evaluate the dependence on temperature, external fields, carrier density, and impurities. We find that the Fröhlich interaction that dominates carrier relaxation contributes negligibly to spin relaxation, consistent with the spin-conserving nature of this interaction. Our theoretical approach may lead to new strategies to optimize spin and carrier transport properties.

Spin-polarized electronic properties of naphthylene-based carbon nanostructures.

The 2D naphthylene-ß structure is a theoretically proposed sp2 nanocarbon allotrope based on the assembly of naphthalene-based molecular building blocks, which features metallic properties. We report that 2D naphthylene-ß structures host a spin-polarized configuration which turns the system into a semiconductor. We analyze this electronic state in terms of the bipartition of the lattice. In addition, we study the electronic properties of nanotubes obtained from the rolling up of 2D naphthylene-ß. We show that they inherit the properties of the parent 2D nanostructure, such as the emergence of spin-polarized configurations. We further rationalize the results in terms of a zone-folding scheme. We also show that the electronic properties can be modulated using an external transverse electric field, including a semiconducting-to-metallic transition for sufficiently large field strength.

Tripentaphenes: two-dimensional acepentalene-based nanocarbon allotropes.

Tripentaphenes are 2D nanocarbon lattices conceptually obtained from the assembly of acepentalene units. In this work, density functional theory is used to investigate their structural, electronic, and vibrational properties. Their bonding configuration is rationalized with a resonance mechanism, which is unique to each of the 2D assemblies. Their formation energies are found to lie within the range of other previously synthesized carbon nanostructures and phonon calculations indicate their dynamical stability. In addition, all studied tripentaphenes are metallic and display different features (e.g., Dirac cone) depending on the details of the atomic structure. The resonance structure also plays an important role in determining the electronic properties as it leads to delocalized electronic states, further highlighting the potential of the structures in nanoelectronics.