Efficient spin filtering through FeGeTe-based van der Waals heterostructures.

Utilizing simulations, we study the spin-dependent electronic transport characteristics within FeGeTe-based van der Waals heterostructures. The electronic density of states for both free-standing and device-configured FeGeTe (F4GT) confirms its ferromagnetic metallic nature and reveals a weak interface interaction between F4GT and PtTe electrodes, enabling efficient spin filtering. The ballistic transport through a double-layer F4GT with a ferromagnetic configuration sandwiched between two PtTe electrodes is predicted to exhibit an impressive spin polarization of 97% with spin-up electrons exhibiting higher transmission probability than spin-down electrons.

Strong In-Plane Magnetization and Spin Polarization in (CoFe)GeTe/Graphene van der Waals Heterostructure Spin-Valve at Room Temperature.

Van der Waals (vdW) magnets are promising, because of their tunable magnetic properties with doping or alloy composition, where the strength of magnetic interactions, their symmetry, and magnetic anisotropy can be tuned according to the desired application. However, so far, most of the vdW magnet-based spintronic devices have been limited to cryogenic temperatures with magnetic anisotropies favoring out-of-plane or canted orientation of the magnetization. Here, we report beyond room-temperature lateral spin-valve devices with strong in-plane magnetization and spin polarization of the vdW ferromagnet (CoFe)GeTe (CFGT) in heterostructures with graphene.

Manipulation of electrochemical properties of MXene electrodes for supercapacitor applications by chemical and magnetic disorder.

The potential of two-dimensional MXenes as electrodes in supercapacitor applications has been studied extensively. However, the role of chemical and magnetic disorder in their electrochemical parameters, , capacitance, has not been explored yet. In this work, we have systematically addressed this for VMnCO MXene solid solutions with an analysis based upon the results from first-principles electronic structure calculations.

Influence of derived site-dependent hopping parameters on electronic transport in graphene nanoribbons.

Graphene Nano Ribbons (GNRs) have been studied extensively due to their potential applications in electrical transport, optical devices, The Tight Binding (TB) model is a common method used to theoretically study the properties of GNRs. However, the hopping parameters of two-dimensional graphene (2DG) are often used as the hopping parameters of the TB model of GNRs, which may lead to inaccuracies in the prediction of GNRs. In this work, we calculated the site-dependent hopping parameters from density functional theory and construction of Wannier orbitals for use in a realistic TB model.

Nonequilibrium Phonon Dynamics and Its Impact on the Thermal Conductivity of the Benchmark Thermoelectric Material SnSe.

Thermoelectric materials play a vital role in the pursuit of a sustainable energy system by allowing the conversion of waste heat to electric energy. Low thermal conductivity is essential to achieving high-efficiency conversion. The conductivity depends on an interplay between the phononic and electronic properties of the nonequilibrium state.

A hexagon based Mn(II) rod metal-organic framework - structure, SF gas sorption, magnetism and electrochemistry.

A manganese(II) metal-organic framework based on the hexatopic hexakis(4-carboxyphenyl)benzene, cpb: [Mn(cpb)(dmf)], was solvothermally prepared showing a Langmuir area of 438 m g, rapid uptake OF sulfur hexafluoride (SF) as well as electrochemical and magnetic properties, while single crystal diffraction reveals an unusual rod-MOF topology.

A Room-Temperature Spin-Valve with van der Waals Ferromagnet Fe GeTe /Graphene Heterostructure.

The discovery of van der Waals (vdW) magnets opened a new paradigm for condensed matter physics and spintronic technologies. However, the operations of active spintronic devices with vdW ferromagnets are limited to cryogenic temperatures, inhibiting their broader practical applications. Here, the robust room-temperature operation of lateral spin-valve devices using the vdW itinerant ferromagnet Fe GeTe in heterostructures with graphene is demonstrated.

Ultralow thermal conductivity and anisotropic thermoelectric performance in layered materials LaMOCh (M = Cu, Ag; Ch = S, Se).

In layered materials with the stacking axis perpendicular to the basal plane, anharmonicity strongly affects phonon propagation due to weak interlayer coupling, which is helpful to reduce the lattice thermal conductivity and improve the thermoelectric (TE) performance significantly. By combining first-principles calculations and the Boltzmann transport equation, we systematically analyzed and evaluated the lattice thermal conductivity and TE properties of LaMOCh (M = Cu, Ag; Ch = S, Se). The results indicate that these layered materials exhibit ultralow lattice thermal conductivities of 0.

Unusual Magnetic Features in Two-Dimensional FeGeTe Induced by Structural Reconstructions.

Recent experiments on FeGeTe suggested the presence of a symmetry breaking of its conventional crystal structure. Here, using density functional theory calculations, we elucidate that the stabilization of the (√3 × √3)30° supercell structure is caused by the swapping of Fe atoms occurring in the monolayer limit. The swapping to the vicinity of Te atoms is facilitated by the spontaneous occurrence of Fe vacancy and its low diffusion barrier.

Unveiling Temperature-Induced Structural Domains and Movement of Oxygen Vacancies in SrTiO with Graphene.

Heterointerfaces coupling complex oxides exhibit coexisting functional properties such as magnetism, superconductivity, and ferroelectricity, often absent in their individual constituent. SrTiO (STO), a canonical band insulator, is an active constituent of such heterointerfaces. Temperature-, strain-, or mechanical stress-induced ferroelastic transition leads to the formation of narrow domains and domain walls in STO.

Large Damping-Like Spin-Orbit Torque in a 2D Conductive 1T-TaS Monolayer.

A damping-like spin-orbit torque (SOT) is a prerequisite for ultralow-power spin logic devices. Here, we report on the damping-like SOT in just one monolayer of the conducting transition-metal dichalcogenide (TMD) TaS interfaced with a NiFe (Py) ferromagnetic layer. The charge-spin conversion efficiency is found to be 0.

Tailoring the opto-electronic response of graphene nanoflakes by size and shape optimization.

The long spin-diffusion length, spin-lifetime and excellent optical absorption coefficient of graphene provide an excellent platform for building opto-electronic devices and spin-based logic in a nanometer regime. In this study, by using density functional theory and its time-dependent version, we provide a detailed analysis of how the size and shape of graphene nanoflakes can be used to alter their magnetic structures and optical properties. As the edges of zigzag graphene nanoribbons are known to align anti-ferromagnetically and armchair nanoribbons are typically non-magnetic, a combination of both in a nanoflake geometry can be used to optimize the ground-state magnetic structure and tailor the exchange coupling decisive for ferro- or anti-ferromagnetic edge magnetism, thereby offering the possibility to optimize the external fields needed to switch magnetic ordering.

Oxygen vacancy in ZnO-phase: pseudohybrid Hubbard density functional study.

The study of zinc oxide, within the homogeneous electron gas approximation, results in overhybridization of zinc 3d shell with oxygen 2p shell, a problem shown for most transition metal chalcogenides. This problem can be partially overcome by using LDA +(or, GGA +) methodology. However, in contrast to the zinc 3d orbital, Hubbard type correction is typically excluded for the oxygen 2p orbital.

Two-Dimensional Square-AB (A = Cu, Ag, Au, and B = S, Se): Auxetic Semiconductors with High Carrier Mobilities and Unusually Low Lattice Thermal Conductivities.

Using evolutionary structure search combined with ab initio theory, we investigate the electronic, thermal, and mechanical properties of two-dimensional (2D) AB (A = Cu, Ag, Au, and B = S, Se) auxetic semiconductors. Two types of structures are found to have low energy, namely, s(I/II)-AB, which have direct bandgaps in the range 1.09-2.

Enhancement of photovoltaic efficiency in CdSe Te (where 0 ⩽ x ⩽ 1): insights from density functional theory.

Recent advancements in CdTe photovoltaic efficiency have come from selenium grading, which reduces the band gap and significantly improves carrier lifetimes. In this work, density functional theory calculations were performed to understand the structural and electronic effects of Se alloying. Special quasirandom structures were used to simulate a random distribution of Se anions.

Density functional study of structural, electronic and magnetic properties of new half-metallic ferromagnetic double perovskite SrMnVO.

In this paper, a new half-metallic (HM) double perovskite compound is predicted with the simultaneous presence of ferromagnetism and polar distortion. The structural, electronic and magnetic properties of SrMnVO (SMVO) are calculated by density functional theory (DFT) with both generalized gradient approximation (GGA) and GGA  +  U approaches, where U is the on-site Coulomb interaction parameter. Different orderings of B (B') cationic sites in ABB'O double perovskite structure are evaluated, including rocksalt, columnar and layered arrangements for cubic, monoclinic and tetragonal crystal structures.

Ligand Effects on the Linear Response Hubbard U: The Case of Transition Metal Phthalocyanines.

It is established that density functional theory (DFT) + U is a better choice compared to DFT for describing the correlated electron metal center in organometallics. The value of the Hubbard U parameter may be determined from linear response, either by considering the response of the metal site alone or by additionally considering the response of other sites in the compound. We analyze here in detail the influence of ligand shells of increasing size on the U parameter calculated from the linear response for five transition metal phthalocyanines.

Controlling the orientation of nucleobases by dipole moment interaction with graphene/h-BN interfaces.

The interfaces in 2D hybrids of graphene and h-BN provide interesting possibilities of adsorbing and manipulating atomic and molecular entities. In this paper, with the aid of density functional theory, we demonstrate the adsorption characteristics of DNA nucleobases at different interfaces of 2D hybrid nanoflakes of graphene and h-BN. The interfaces provide stronger binding to the nucleobases in comparison to pure graphene and h-BN nanoflakes.

Publisher Correction: Atomic-scale engineering of ferroelectric-ferromagnetic interfaces of epitaxial perovskite films for functional properties.

A correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.

A systematic study of 4d and 5d transition metal mediated exchange coupling between Fe and Gd nanolaminates.

We present a systematic study of the magnetic coupling between iron and gadolinium layers intermediated by 4d and 5d transition metals using density functional theory. We demonstrate that it is possible to find a magnetic coupling for most of them. In particular, for the early transition metals (d , d , d and d ), a ferromagnetic coupling occurs even stronger than the 3d interlayers.

Atomic-scale engineering of ferroelectric-ferromagnetic interfaces of epitaxial perovskite films for functional properties.

Besides epitaxial mismatch that can be accommodated by lattice distortions and/or octahedral rotations, ferroelectric-ferromagnetic interfaces are affected by symmetry mismatch and subsequent magnetic ordering. Here, we have investigated La Sr MnO (LSMO) samples with varying underlying unit cells (uc) of BaTiO (BTO) layer on (001) and (110) oriented substrates in order to elucidate the role of symmetry mismatch. Lattice mismatch for 3 uc of BTO and symmetry mismatch for 10 uc of BTO, both associated with local MnO octahedral distortions of the (001) LSMO within the first few uc, are revealed by scanning transmission electron microscopy.

New quaternary half-metallic ferromagnets with large Curie temperatures.

New magnetic materials with high Curie temperatures for spintronic applications are perpetually sought for. In this paper, we present an ab initio study of the structural, electronic and magnetic properties of Quaternary Heusler compounds CoX'Y'Si where X' is a transition metal with 4d electrons and Y' is either Fe or Mn. We find five new half-metallic ferromagnets with spin polarisation nearly 100% with very high Curie temperatures.

Metal-free photochemical silylations and transfer hydrogenations of benzenoid hydrocarbons and graphene.

The first hydrogenation step of benzene, which is endergonic in the electronic ground state (S), becomes exergonic in the first triplet state (T). This is in line with Baird's rule, which tells that benzene is antiaromatic and destabilized in its T state and also in its first singlet excited state (S), opposite to S, where it is aromatic and remarkably unreactive. Here we utilized this feature to show that benzene and several polycyclic aromatic hydrocarbons (PAHs) to various extents undergo metal-free photochemical (hydro)silylations and transfer-hydrogenations at mild conditions, with the highest yield for naphthalene (photosilylation: 21%).

Recipe for High Moment Materials with Rare-earth and 3d Transition Metal Composites.

Materials with high volume magnetization are perpetually needed for the generation of sufficiently large magnetic fields by writer pole of magnetic hard disks, especially for achieving increased areal density in storage media. In search of suitable materials combinations for this purpose, we have employed density functional theory to predict the magnetic coupling between iron and gadolinium layers separated by one to several monolayers of 3d transition metals (Sc-Zn). We demonstrate that it is possible to find ferromagnetic coupling for many of them and in particular for the early transition metals giving rise to high moment.

Polar Order and Frustrated Antiferromagnetism in Perovskite Pb2MnWO6 Single Crystals.

Single crystals of the multiferroic double-perovskite Pb2MnWO6 have been synthesized and their structural, thermal, magnetic and dielectric properties studied in detail. Pure perovskite-phase formation and stoichiometric chemical composition of the as-grown crystals are confirmed by X-ray single-crystal and powder diffraction techniques as well as energy-dispersive X-ray and inductively coupled plasma mass spectrometry. Detailed structural analyses reveal that the crystals experience a structural phase transition from the cubic space group (s.