Yttria-stabilized zirconia (YSZ) is a widely recognized ceramic of distinct electrical, mechanical and optical properties. Although YSZ is an intrinsically paramagnetic solid, it could potentially ...transform to a magnetic semiconductor by incorporating in its crystalline structure isolated atoms bearing unpaired valence electrons. Based on this hypothesis and motivated by the latest advances on YSZ doped with rare-earth atoms, in the current article we report on the electronic and magnetic properties of YSZ doped with Er
3+
(Xe4f
11
6s
0
) cations that comprise three “unpaired” 4f electrons in their ground state electronic configuration. Our computations, conducted on YSZ 6.7 mol% in Y
2
O
3
doped with two different Er
3+
concentrations (3.2 and 6.7 mol% in Er
2
O
3
), expose that Er
3+
:YSZ is a stable antiferromagnetic semiconductor (
S
=
3
2
per Er
+3
) bearing a rather wide band gap of about 5 eV. All results presented and discussed in current report rely on spin–polarized density functional theory (DFT) within the spin resolved generalized gradient approximation (SGGA) for the pure Perdew, Burke and Ernzerhof exchange–correlation functional (PBE) and hybrid version widely referred as PBE0. According to our knowledge, this is the first time that the magnetic properties of Er
3+
: YSZ materials are reported for any Er
+3
concentration.
We report on the successful on-surface polymerization reaction of codeposited zwitterionic quinones with Fe atoms on Au(110) at an appropriate temperature. The resulting covalent one-dimensional ...polymer chains arrange in a well-ordered two-dimensional (2D) structure as proven by scanning tunneling microscopy and low-energy electron diffraction. The ordered regions can reach the micrometer size. Furthermore, the electronic and magnetic properties of the zwitterionic quinoidal polymers on Au(110) were investigated using the density functional theory with an explicit inclusion of the Hubbard U term. The spin-polarized generalized gradient approximation plus U method (SGGA + U) has been used, and the freestanding isolated polymer chain, the 2D arrangement, and the adsorbed polymers have been calculated. From ab initio calculations, we predict the zwitterionic quinoidal polymer chains to be a one-dimensional spin crossover compound. For the freestanding chains, we find two local minima with comparable energies but different spin states: a high-spin state (S = 2 per Fe) with an Fe–Fe distance of 7.9 Å and an intermediate-spin state (S = 1) with an Fe–Fe distance of 7.72 Å. The experimental and theoretical results show that the substrate dictates the lattice constant, and the adsorbed polymer on Au(110) has an Fe–Fe distance of 8.16 Å and is in the high-spin state. The exchange coupling in the polymeric chain with the Au(110) lattice constants was found to be antiferromagnetic. The adsorption on Au(110) removes the surface reconstruction of a free surface, and the ab initio simulation gives the short-bridge position for Fe as the most stable one.
The supramolecular self-assembly of
-indacene-1,3,5,7(2
,6
)-tetrone on the Cu(111) surface was investigated under ultrahigh vacuum by room-temperature scanning tunneling microscopy supported by ...theoretical modelling based on density functional theory. In total, six different phases were found, driven by hydrogen bonding, metal ligand coordination or covalent coupling. Host-guest interactions allowed for the accommodation of molecular or metal clusters inside the open nanoporous patterns. In one phase, molecular trapping was stochastically observed inside the large periodic nanopores created inside the supramolecular network. The three metal-organic networks observed resulted in the creation of different kinds of regular arrays of isolated metal adatoms or adatom clusters with a lattice period larger than 1 nm.
Ab initio calculations based on density functional theory (DFT) including an explicit treatment of the strong electron correlation in the d shell of the transition metal ions have been conducted ...using the spin-polarized generalized gradient approximation with Hubbard term U (SGGA+U) to investigate systematically the electronic and magnetic properties of a new material class representing one-dimensional transition metal zwitterionic quinone (TM-ZQ) polymers having many potential applications, especially in spintronics. The complete class of 3d transition metals (TMs) are investigated from Sc to Zn. Zn-ZQ is nonmagnetic, since it has a 3d10 configuration. All of the other TM-ZQ polymers are antiferromagnetic semiconductors with the exception of Mn-ZQ that is metallic for the ferromagnetic (FM) and the antiferromagnetic (AFM) spin arrangements and Sc-ZQ and Ti-ZQ which are FM semiconductors. All of these polymer chains have the potential to be produced by on-surface synthesis on metallic surfaces, as was recently shown for Fe-ZQ (Koudia, M.; et al. Nano Res. 2017, 10, 933–940).
Yttria-stabilized zirconia (YSZ) is a widely recognized ceramic of distinct electrical, mechanical and optical properties. Although YSZ is an intrinsically paramagnetic solid, it could potentially ...transform to a magnetic semiconductor by incorporating in its crystalline structure isolated atoms bearing unpaired valence electrons. Based on this hypothesis and motivated by the latest advances on YSZ doped with rare-earth atoms, in the current article we report on the electronic and magnetic properties of YSZ doped with Er.sup.3+ (Xe4f.sup.116s.sup.0) cations that comprise three "unpaired" 4f electrons in their ground state electronic configuration. Our computations, conducted on YSZ 6.7 mol% in Y.sub.2O.sub.3 doped with two different Er.sup.3+ concentrations (3.2 and 6.7 mol% in Er.sub.2O.sub.3), expose that Er.sup.3+:YSZ is a stable antiferromagnetic semiconductor ( Formula omitted per Er.sup.+3) bearing a rather wide band gap of about 5 eV. All results presented and discussed in current report rely on spin-polarized density functional theory (DFT) within the spin resolved generalized gradient approximation (SGGA) for the pure Perdew, Burke and Ernzerhof exchange-correlation functional (PBE) and hybrid version widely referred as PBE0. According to our knowledge, this is the first time that the magnetic properties of Er.sup.3+: YSZ materials are reported for any Er.sup.+3 concentration.
•Ab-initio proposal of new magnetic semiconductor polymers.•Metal-organic polymers of zwitterionic quinone (ZQ) with 4d and 5d transition metals.•Large values of spin-orbit coupling lead to high ...magnetic anisotropy energies.•Especially high magnetic anisotropy for Rh-ZQ and Re-ZQ.•Potential candidates for specific applications in nano spintronics.
The electronic and magnetic properties of one-dimensional polymers of zwitterionic quinone (ZQ) molecules with 4d and 5d transition metals (TM) are studied using density functional calculations. We present the results of first-principle calculations for the electronic and magnetic properties, including the magnetic anisotropy energy (MAE) of selected 4d- and 5d-ZQ polymers, using the Vienna Ab-initio Simulation Package (VASP). In particular, a pronounced magnetic character is found for TM-ZQ polymers with the TM ions Mo, Ru, Rh, Ag, Re, and Ir, having local magnetic moments between 1 and 4 μB and ferromagnetic or antiferromagnetic nearest neighbor exchanges. The large values of spin–orbit coupling lead to high magnetic anisotropy energies (MAE) especially for Rh-ZQ and Re-ZQ, exceeding the MAE of its 3d counterparts considerably. All investigated TM-ZQ polymer chains were found to be spin-polarized semiconductors, which make them, together with the high MAE, excellent candidate materials for spintronics.
Gap switching in metal-organic coordination chains Denawi, Hassan; Abel, Mathieu; Boukortt, Abdelkader ...
Journal of magnetism and magnetic materials,
10/2022, Letnik:
560, Številka:
23
Journal Article
Recenzirano
Odprti dostop
•New magnetic Metal-organic quinoidal polymer Chains are proposed on the basis density functional theory (DFT) calculations.•One-dimensional Metal–Organic Metallic Antiferromagnetic.•Spin-polarized ...calculations predict the FM semiconducting polymers with a very small energy gap of only 90 meV can be converted to an AFM semiconductor with a large gap of more than 1 eV when oxidized by chlorine.•Band gaps and physical properties of Metal-organic quinoidal polymer suggests their potential candidates for specific applications in Nano electronics and spintronics.
We predict two switchable one-dimensional (1D) spin-polarized semiconductors based on metal-organic coordination chains constructed out of Fe, V, and zwitterionic quinone (ZQ) molecules using first-principle density functional theoretical analysis. The Fe-ZQ coordination chain can be converted from a semiconductor to a half-metal when oxidized by chlorine (Cl). Upon chlorination, the magnetic moment of the Fe-ZQ is increased from 4 μB to 5 μB, per iron atom. In addition, the bimetallic (Fe-ZQ-V-ZQ) ferromagnetic semiconducting coordination chain with a very small energy gap of only 90 meV can be converted to an antiferromagnetic semiconductor with a large gap of more than 1 eV when oxidized by chlorine. Its magnetic moment is found to be 8 μB per heterobimetallic unit (Fe and V) after chlorination, and 7 μB without chlorine. These unique properties, namely a switchable or reversible electronic and magnetic characteristics with a transition between different semiconducting states, make these coordination chains to be highly promising candidates for specific applications as multi-functional switch in nanoelectronics and spintronics.
On-surface polymerization of iron atoms and zwitterion quinone (ZQ) molecules on Ag(111) is studied experimentally under ultrahigh vacuum and theoretically in the framework of density functional ...theory. The resulting one-dimensional (1D) polymer chain is a promising model system to study both magnetic and conductive properties in one dimension. Previously we have shown that such polymer synthesis is possible over large scale by a controlled codeposition of the two elements (i.e., metal and molecule) on a Ag(111) substrate (Nano Res. 2017, 10, 933). In that case, polymer chains are bound together to form a two-dimensional (2D) arrangement of spin chains influencing the magnetic properties of individual chains. Here we show that individual chains can be obtained using a sequential deposition of first metals and then ligands by scanning tunnelling microscopy on the Ag(111) surface. Ab initio calculations are used to compare the atomic, electronic, and magnetic structures of isolated Fe-ZQ polymer chains (1D) to the previously obtained two-dimensional (2D) arrangement of the polymer chains. The adsorption energy is determined using the spin-polarized generalized gradient approximation (SGGA) and the SGGA+U approximation. It yields small values of less than 530 meV per Fe. On the Ag(111) surface, the most favorable adsorption site of Fe in the polymer chain is the hexagonal close-packed (hcp) site for the 1D polymer, but it changes to the face-centered-cubic (fcc) site for the 2D polymer. Using both SGGA and SGGA+U methods, we find a small difference between the two sites: face-centered-cubic (fcc) and hexagonal-close-packed (hcp). This latter is the most stable adsorption energy when we add the Hubbard U term to the SGGA method.
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•The NLO capacity of YSZ is comparable to YSZ.•Evidence of significant vibrational contributions to the optical third order nonlinearities of Yttria stabilized hafnia are ...reported.•The electronic properties of YSH do not constitute subjects of strong spin orbit coupling effects.
This work reports for the first time theoretical third order nonlinear optical susceptibilities of YSH bulk phases which are key properties for telecommunication technologies and integrated photonic devices. Our outcomes, relying on coupled perturbed Kohn-Sham density functional theory expose that the NLO capacity of YSH should be similar to another material of this family, namely, yttria stabilized zirconia that has been proposed as a promising candidate for integrated photonics by Marcaud et al. (2020). Finally, evidence implying important vibrational contributions to the optical nonlinearities of the systems are revealed and analyzed.
The synthesis and optoelectronics properties of polyaromatic hydrocarbons (PAHs) doped with boron and nitrogen units (BN) monopolize the interest of increasing numbers of researchers the past few ...years. The key concept fueling these attempts lies on the prospect of engineering novel organic compounds of versatile physical and chemical properties using well-known all-carbon systems as scaffolds. Among the various BN-doped PAHs synthesized so far, one could distinguish two categories. The most common one comprises systems in which BN units replace aromatic CC bonds. The second one, which this study deals with, refers to systems wherein the BN unit replaces intercyclic CC bonds linking two independent aromatic sextets within the framework of a given PAH. In this work, starting from a reference molecule belonging to the latter category, namely, the pyridine-adduct of borazine, we open the subject of PAHs doped with intercyclic boron nitrogen bonds. Our results, based on state-of-the-art ab initio and density functional theory wavefunction methods, suggest that intercyclic BN bonds, referred in the literature as “N → B dative bonds”, if successfully incorporated to (in)finite polyaromatic sections, may alter the optical absorption profiles of the parental systems in a greater extent than typical BN aromatic units. Specifically, we predict and comprehensively interpret the capacity of N → B dative bonds to switch-on extra-strong one- and two-photon quantum transitions followed by intense transfer of charge. The strong excited-states alternation triggered by the presence of N → B dative bonds may unleash exceptionally high nonlinear optical responses and could find a proper ground in organic optoelectronic technologies.
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