4 research outputs found
Double Kagome Bands in a Two-Dimensional Phosphorus Carbide P<sub>2</sub>C<sub>3</sub>
The interesting properties of Kagome
bands, consisting of Dirac
bands and a flat band, have attracted extensive attention. However,
materials with only one Kagome band around the Fermi level cannot
possess physical properties of Dirac Fermions and strong correlated
Fermions simultaneously. Here, we propose a new type of band structure,
double Kagome bands, which can realize coexistence of the two kinds
of Fermions. Moreover, the new band structure is found to exist in
a new two-dimensional material, phosphorus carbide P<sub>2</sub>C<sub>3</sub>. The carbide material shows good stability and unusual electronic
properties. Strong magnetism appears in the structure by hole doping
of the flat band, which results in spin splitting of the Dirac bands.
The edge states induced by Dirac and flat bands coexist on the Fermi
level, indicating outstanding transport characteristics. In addition,
a possible route to experimentally grow P<sub>2</sub>C<sub>3</sub> on some suitable substrates such as the Ag(111) surface is also
discussed
Dirac Nodal Lines and Tilted Semi-Dirac Cones Coexisting in a Striped Boron Sheet
The
enchanting Dirac fermions in graphene stimulated us to seek
other 2D Dirac materials, and boron monolayers may be a good candidate.
So far, a number of monolayer boron sheets have been theoretically
predicted, and three have been experimentally prepared. However, none
of intrinsic sheets possess Dirac electrons near the Fermi level.
Herein, by means of density functional theory computations, we identified
a new boron monolayer, namely, hr-sB, with two types of Dirac fermions
coexisting in the sheet: One type is related to Dirac nodal lines
traversing Brillouin zone (BZ) with velocities approaching 10<sup>6</sup> m/s, and the other is related to tilted semi-Dirac cones
with strong anisotropy. This newly predicted boron monolayer consists
of hexagon and rhombus stripes. With an exceptional stability comparable
to the experimentally achieved boron sheets, it is rather optimistic
to grow hr-sB on some suitable substrates such as the Ag (111) surface
Electrostatic Gating of Spin Dynamics of a Quasi-2D Kagome Magnet
Electrostatic
gating has emerged as a powerful technique for tailoring
the magnetic properties of two-dimensional (2D) magnets, offering
exciting prospects including enhancement of magnetic anisotropy, boosting
Curie temperature, and strengthening exchange coupling effects. Here,
we focus on electrical control of the ferromagnetic resonance of the
quasi-2D Kagome magnet Cu(1,3-bdc). By harnessing an electrostatic
field through ionic liquid gating, significant shifts are observed
in the ferromagnetic resonance field in both out-of-plane and in-plane
measurements. Moreover, the effective magnetization and gyromagnetic
ratios display voltage-dependent variations. A closer examination
reveals that the voltage-induced changes can modulate magnetocrystalline
anisotropy by several hundred gauss, while the impact on orbital magnetization
remains relatively subtle. Density functional theory (DFT) calculations
reveal varying d-orbital hybridizations at different voltages. This
research unveils intricate physics within the Kagome lattice magnet
and further underscores the potential of electrostatic manipulation
in steering magnetism with promising implications for the development
of spintronic devices
[Ti<sub>8</sub>Zr<sub>2</sub>O<sub>12</sub>(COO)<sub>16</sub>] Cluster: An Ideal Inorganic Building Unit for Photoactive Metal–Organic Frameworks
Metal–organic frameworks (MOFs)
based on Ti-oxo clusters
(Ti-MOFs) represent a naturally self-assembled superlattice of TiO<sub>2</sub> nanoparticles separated by designable organic linkers as
antenna chromophores, epitomizing a promising platform for solar energy
conversion. However, despite the vast, diverse, and well-developed
Ti-cluster chemistry, only a scarce number of Ti-MOFs have been documented.
The synthetic conditions of most Ti-based clusters are incompatible
with those required for MOF crystallization, which has severely limited
the development of Ti-MOFs. This challenge has been met herein by
the discovery of the [Ti<sub>8</sub>Zr<sub>2</sub>O<sub>12</sub>Â(COO)<sub>16</sub>] cluster as a nearly ideal building unit for photoactive
MOFs. A family of isoreticular photoactive MOFs were assembled, and
their orbital alignments were fine-tuned by rational functionalization
of organic linkers under computational guidance. These MOFs demonstrate
high porosity, excellent chemical stability, tunable photoresponse,
and good activity toward photocatalytic hydrogen evolution reactions.
The discovery of the [Ti<sub>8</sub>Zr<sub>2</sub>O<sub>12</sub>Â(COO)<sub>16</sub>] cluster and the facile construction of photoactive MOFs
from this cluster shall pave the way for the development of future
Ti-MOF-based photocatalysts