Using density functional theory (OLYP/STO-TZP) calculations, we have investigated the electronic structure of [Mn(5,5-tropocoronand)(NO)], a rare paramagnetic {MNO}(6) complex. Experimental methods, including magnetic susceptibility measurements and high-field electron paramagnetic resonance spectroscopy, have not provided an unambiguous spin state assignment for this complex. In other respects...

High-resolution angle-resolved photoelectron spectroscopy is used to examine the electronic band structure of FeTe_{0.5}Se_{0.5} near the Brillouin zone center. A consistent separation of the α_{1} and α_{2} bands is observed with little k_{z} dependence of the α_{1} band. First-principles calculations for bulk and thin films demonstrate that the antiferromagnetic coupling between the Fe atoms ...

Sr$_2$RuO$_4$ has been under intensive scrutiny over the past years after new NMR measurements unveiled that superconducting state might be a spin singlet. One of best order parameter candidates in light these experiments is chiral d-wave with $d_{xz}+id_{yz}$ symmetry. This overlooked given strong two-dimensional character normal electronic structure. Recently, phenomenological proposal based ...

We introduce a one-dimensional (1D) XZ model with alternating σ i σ z i+1 and σ x i σ x i+1 interactions on even/odd bonds, interpolating between the Ising model and the quantum compass model. We present two ways of its exact solution by: (i) mapping to the quantum Ising models, and (ii) using fermions with spin 1/2. In certain cases the nearest neighbor pseudospin correlations change discontin...

Abstract The photoproduction processes of the exotic Θ+(1540) baryon and the K ∗ meson from the nucleon targets, i.e., γn → K∗−Θ+ and γp → K̄∗0Θ+, are investigated in a hadronic model. We consider K and K∗ exchanges as well as the s and u channel nucleon and Θ terms. Various spin asymmetries together with cross sections are first computed in order to study the production mechanisms and the parit...

A clear physics picture of TbBaCo2O5.5 is revealed on the basis of density functional theory calculations. An antiferromagnetic (AFM) superexchange coupling between the almost high-spin Co ions competes with a ferromagnetic (FM) interaction mediated by both p-d exchange and double exchange, being responsible for the observed AFM-FM transition. And the metal-insulator transition is accompanied b...

For the antiferromagnetic, highly anisotropic XZ and XXZ quantum spin chains, we impose periodic boundary conditions on chains with an odd number of sites to force an interface (or kink) into the chain. We prove that the energy of the interface depends on the momentum of the state. This shows that at zero temperature the interface in such chains is not stable. This is in contrast to the ferroma...

High-spin square-planar molecular compounds are rare. In an effort to access this unique combination of geometry and spin state, we report the synthesis of a series of M(II) compounds stabilized by a trianionic pincer-type ligand, highlighting the formation of a high-spin square-planar Co(II) complex. Low-temperature, variable-frequency EPR measurements reveal that the ground electronic state o...

We present new 7 mm and archive 1.3 cm high angular resolution observations of the HL/XZ Tau region made with the VLA. At 7 mm, the emission from HL Tau seems to be arising in a clumpy disk with radius of order 25 AU. The 1.3 cm emission from XZ Tau shows the emission from a binary system with 0.3 (42 AU) separation, known from previous optical/IR observations. However, at 7 mm, the southern ra...

We calculate the conductance as a function of temperature G(T) through Au monatomic chains containing one Co atom as a magnetic impurity, and connected to two conducting leads with a fourfold symmetry axis. Using the information derived from ab initio calculations, we construct an effective model Ĥ(eff) that hybridizes a 3d(7) quadruplet at the Co site with two 3d(8) triplets through the hoppin...