Through first-principles calculations, we study the electronic structure of double-perovskite iridates with Ir in ${d}^{4}$ valence state. Contrary to expected strong spin-orbit driven $J=0$ nonmagnetic state, find finite moment at site, exhibiting breakdown We further band effect rather than crystal field be responsible for this breakdown. The antiferromagnetic superexchange interaction between moments, general, makes these compounds insulating.

Using first-principles density functional calculations, we study the electronic structure of double perovskite compound, La${}_{2}$CoMnO${}_{6}$, which is reported to be ferromagnetic insulator with a Curie temperature about 240 K. Our calculations show that insulating state in this compound driven by Coulomb-assisted spin-orbit coupling operative within Co-$d$ manifold, rather large orbital moment $\ensuremath{\approx}$0.17 ${\ensuremath{\mu}}_{B}$ at Co site. Motivated report...

We report the magnetic and electronic transport properties of inversion time-reversal symmetry breaking Weyl semimetal NdAlGe. This material is analogous to NdAlSi, whose helical magnetism presents a rare example Weyl-mediated collective phenomenon, but with larger spin-orbit coupling. Our neutron diffraction experiments revealed that NdAlGe, similar supports an incommensurate spin density wave (${T}_{\text{inc}}=6.8$ K) spins are predominantly pointing along out-of-plane direction have...

In this work, we report the study of electronic structure, magnetism, and existence Weyl nodes in a pristine bulk FeNi$_{3}$, member Fe-Ni inver alloy compounds, known as good metal catalysts with high activity stability for water splitting very long time. Our observation points FeNi$_{3}$ may lead to new technology design highly efficient topological catalysts. While previous literature \cite{PhysRev.97.304} mainly focused on thermal catalytic properties interplay Fe $d$-Ni $d$...

We present results indicating that Chern insulator states can be achieved in the recently synthesized pristine chromium triiodide (${\mathrm{CrI}}_{3}$) by either electron or hole doping. Our first-principles density-functional-theory calculations confirmed monolayer ${\mathrm{CrI}}_{3}$ show nontrivial number $C$ both valence and conduction bands. By introducing on-site Coulomb interaction epitaxial strain, doped exhibit a series of topological quantum phase transitions between multiple...

Perovskite bilayers with (111)-orientation combine a honeycomb lattice as key feature the strongly correlated, multiorbital nature of electrons in transition metal oxides. In systematic DFT+$U$ study (111)-oriented (La$X$O$_3$)$_2$/(LaAlO$_3$)$_4$ superlattices, we establish trends evolution ground states versus band filling $X$ spanning entire $3d$ series. The competition between local quasi-cubic and global triangular symmetry triggers unanticipated broken phases, mechanisms ranging from...

Abstract Based on first-principles density-functional theory (DFT) calculations, we report that the transition-metal bis-dithiolene, M 3 C 12 S ( = Mn and Fe), complexes can be a two-dimensional (2D) ferromagnetic insulator with nontrivial Chern number. Among various synthetic pathways leading to metal bis-dithiolenes, simplest choice of ligand, Benzene-hexathiol, connecting cations form Kagome lattice is studied following experimental time-reversal symmetric isostructural compound Ni . We...

The binary intermetallic materials, $M_3$Sn$_2$ ($M$ = 3d transition metal) present a new class of strongly correlated systems that naturally allows for the interplay magnetism and metallicity. Using first principles calculations we confirm bulk Fe$_3$Sn$_2$ is ferromagnetic metal, show $M$ Ni Cu are paramagnetic metals with non-trivial band structures. Focusing on to understand effect enhanced correlations in an experimentally relevant atomistically thin single kagome-bilayer, our ab-initio...

Towards the goal of realizing topological phases in thin films correlated oxide and heterostructures, we propose here a quantum anomalous Hall insulator (QAHI) ultrathin double perovskites based on mixed $3d\ensuremath{-}5d$ or $3d\ensuremath{-}4d$ transition-metal ions, grown along [111] direction. Considering specific case ${\mathrm{Ba}}_{2}{\mathrm{FeReO}}_{6}$, present theoretical analysis an effective Hamiltonian derived from first principles. We establish that strong spin-orbit...

Time-reversal broken Weyl semimetals have attracted much attention recently, but certain aspects of their behavior, including the evolution Fermi surface topology and anomalous Hall conductivity with Fermi-level position, remained underexplored. A promising route to obtain such materials may be start a nonmagnetic Dirac semimetal break time-reversal symmetry via magnetic doping or proximity. Here we explore this scenario in case ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$ based on first-principles...

Employing first-principles calculations, we provide microscopic insights on the curious magnetic and topological properties of LaCoO3/SrIrO3 heterostructure, which has been recently synthesized [Kumar Jaiswal et al., Adv. Mater. 34, 2109163 (2022)]. Our computational study unravels transfer polar charge from SrIrO3 to LaCoO3, thereby reducing Co valence 3+ toward 2+, supporting experimental findings. further reveals stabilization intermediate spin state strong ferromagnetic Co–Co coupling in...

Mixed sodium nickel hydroxide phosphate, Na2Ni3(OH)2(PO4)2, has been synthesized hydrothermally from the system NiCO3-Na4P2O7-NaCl-H2O. Its monoclinic crystal structure determined by single X-ray diffraction: a = 14.259(5), b 5.695(2), c 4.933(1) Å, β 104.28(3)°, space group C2/m, Z 2, ρc 3.816 g cm(-3), R 0.026. The underlying spin model characterized in terms of first-principles electronic calculations. compound is formed alternating layers [NiO6] octahedra and [NaO7] polyhedra, combined...

Transition metal oxides exhibit various competing phases and exotic phenomena depending on how their reaction to the rich degeneracy of $d$-orbital. Large spin-orbit coupling (SOC) reduces this in a unique way by providing spin-orbital-entangled ground state for 4$d$ 5$d$ transition compounds. In particular, Kramers doublet, known as $J_{\mathbf{eff}}$=1/2 pseudospin, appears layered iridates $\alpha$-RuCl$_3$, manifesting relativistic Mott insulating phase. Such entanglement, however, seems...

We construct an effective spin Hamiltonian for YMn${}_{2}$O${}_{5}$ through analysis of first-principles density-functional theory results. Using our first-principles-derived we calculate the magnon dispersion this compound and compare with experimentally measured spectra probed using inelastic neutron scattering. Our set magnetic interaction parameters show importance Mn1-Mn2 along $b$ axis, which was ignored in literature. provide justification favor parameters.

Using density functional theory calculations, we establish that the half-metallicity of bulk ${\mathrm{Ba}}_{2}{\mathrm{FeReO}}_{6}$ survives down to 1 nm thickness in ${\mathrm{BaTiO}}_{3}/{\mathrm{Ba}}_{2}{\mathrm{FeReO}}_{6}/{\mathrm{BaTiO}}_{3}$ heterostructures grown along (001) and (111) directions. The confinement two-dimensional (2D) electron gas this quantum well structure arises from suppressed hybridization between Re/Fe $d$ states unoccupied Ti states, it is further strengthened...

Using first-principles, density functional theory based calculations, we explore the microscopic origin of switching from antiferromagnetic to ferromagnetic behavior, in replacing Sr by Ca Sr${}_{2}$CrSbO${}_{6}$ double perovskite. Our study reveals that difference strength covalency between and Cr compared Cr, added structural differences, dictates sign dominant first nearest-neighbor Cr-Cr interaction, thereby, is responsible factor for this interesting behavior. The antiferromagnetically...

Using density functional theory calculations including an on-site Coulomb term, we explore electronic and possibly topologically nontrivial phases in $3d$ transition-metal oxide honeycomb layers confined the corundum structure ($\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}$) along [0001] direction. In most cases ground state is a trivial antiferromagnetic Mott insulator, often with distinct orbital or spin states compared to bulk phases. With imposed symmetry of...

We explore dynamic interactions between the crystal lattice and magnetic degrees of freedom in a frustrated system using example pyrochlore quantum spin-ice candidate ${\mathrm{Pr}}_{2}{\mathrm{Zr}}_{2}{\mathrm{O}}_{7}$. Using Raman scattering spectroscopy we demonstrate that electric field excitations Pr3+, which define properties ${\mathrm{Pr}}_{2}{\mathrm{Zr}}_{2}{\mathrm{O}}_{7}$, cannot be understood within model static lattice. identify vibronic with phonon lead to splitting doublet...

Magnetic materials with pyrochlore crystal structure form exotic magnetic states due to the high lattice frustration. In this work we follow effects of coupling and electronic degrees freedom in two praseodymium-based pyrochlores ${\mathrm{Pr}}_{2}{\mathrm{Zr}}_{2}{\mathrm{O}}_{7}$ ${\mathrm{Pr}}_{2}{\mathrm{Ir}}_{2}{\mathrm{O}}_{7}$. either these materials, presence interactions does not lead magnetically ordered low temperature states; however, their properties are different. A comparison...

A new compound, Rb2Cu3(P2O7)2, has been obtained from the melt in Rb–Cu–P–O system. Its monoclinic crystal structure was determined by single-crystal X-ray diffraction: space group P21/c, Z = 2, a 7.7119(8) Å, b 10.5245(9) c 7.8034(9) β 103.862(5)° at 293 K, R 0.030. The copper ions show coordination number (CN) 6 (4+2, distorted tetragonal bipyramidal). Trimers of [CuO6] polyhedra sharing cis-edges form together with diphosphate groups two tetrahedra [P2O7] microporous 3D framework channels...

We carry out a comparative study of the electronic structure two pyrochlore ruthenate compounds, Tl${}_{2}$Ru${}_{2}$O${}_{7}$ and Hg${}_{2}$Ru${}_{2}$O${}_{7}$, in terms first principles calculations. Our reveals Ru $d$ electrons Hg${}_{2}$Ru${}_{2}$O${}_{7}$ to be much more delocalized compared that Tl${}_{2}$Ru${}_{2}$O${}_{7}$. The subtle change Ru-$d$ bandwidths triggered by differences Hg 5$d$--Ru 4$d$ hybridization Tl 4$d$, bring observed behavior. further shows development long range...

Emergent relativistic quasiparticles in Weyl semimetals are the source of exotic electronic properties such as surface Fermi arcs, anomalous Hall effect, and negative magnetoresistance, all observed real materials. Whereas these phenomena highlight effect fermions on transport properties, less is known about what collective they may support. Here, we report a new semimetal, NdAlSi that offers an example. Using neutron diffraction, long-wavelength magnetic order whose periodicity linked to...