Related papers: Spin dynamics in itinerant antiferromagnet SrCr$_2…
We study Heisenberg spin-1/2 and spin-1 chains with alternating ferromagnetic ($J_1^F$) and antiferromagnetic ($J_1^A$) nearest-neighbor interactions and a ferromagnetic next-nearest-neighbor interaction ($J_2^F$). In this model frustration…
We study spin resonance in the superconducting state of recently discovered alkali-intercalated iron selenide materials A_xFe_(2-y)Se_2 (A=K,Rb,Cs) in which the Fermi surface has only electron pockets. Recent angle-resolved photoemission…
We report a neutron scattering study of the metallic triangular lattice antiferromagnet PdCrO$_2$. Powder neutron diffraction measurements confirm that the crystalline space group symmetry remains $R\bar{3}m$ below $T_N$. This implies that…
Inelastic neutron scattering measurements demonstrate that the magnetic interactions in antiferromagnetic LaFeAsO are two-dimensional. Spin wave velocities within the Fe layer and the magnitude of the spin gap are similar to the…
The electronic and magnetic structure, including the Heisenberg model exchange interaction parameters, was explored for the recently proposed novel cuprate Cu$_2$F$_5$. Using the DFT+U calculation, it is shown that the compound is formed by…
We present specific-heat and neutron-scattering results for the \emph{S}=1/2 quantum antiferromagnet (dimethylammonium)(3,5-dimethylpyridinium)CuBr$_4$. The material orders magnetically at \emph{T}$_N$=1.99(2)\,K, and magnetic excitations…
The spin fluctuations in the normal state of the unconventional superconductor Sr2RuO4 have been studied using inelastic neutron scattering with polarization analysis on single crystals. We find that the spin fluctuations are anisotropic…
We report inelastic neutron scattering (INS) investigations on the bilayer Fe-based superconductor CsCa2Fe4As4F4 above and below its superconducting transition temperature Tc = 28.9 K to investigate the presence of a neutron spin resonance.…
Elastic and inelastic neutron scattering were used to study the ordered phase of the quasi-one-dimensional spin-1/2 antiferromagnet ${\rm BaCu_{2}Si_{2}O_{7}}$. The previously proposed model for the low-temperature magnetic structure was…
We present a theoretical and experimental study of a quasi-one-dimensional zigzag antiferromagnet (N_2H_5)CuCl_3, which can be viewed as weakly coupled Heisenberg chains with a frustrated interaction. We first discuss generic features of…
We show that the neutron scattering spectra observed in CaFe$_2$As$_2$ by Zhao et al (arXiv:0903.2686v1) and the highly unusual spatially anisotropic exchange constants in the iron pnictides derived by Han et al (Phys. Rev. Lett. 102,…
The antiferromagnetism in transition metal compounds is mostly mediated by the bridging anions through a so-called superexchange mechanism. However, in materials like normal spinels $AB_2X_4$ with local moments only at the $A$ site, such an…
We report a detailed examination the magnetic structure of anhydrous cupric chloride CuCl2 carried out by powder neutron diffraction, magnetic susceptibility and specific heat measurements on polycrystalline and single crystal samples as…
We investigate the dynamical spin structure factor S(q,w) for the Heisenberg chain with ferromagnetic nearest (J1<0) and antiferromagnetic next-nearest (J2>0) neighbor exchange using bosonization and a time-dependent density-matrix…
We examine the spin and charge excitations in antiferromagnetic iron pnictides by mean-field calculations with a random phase approximation in a five-band itinerant model. The calculated excitation spectra reproduce well spin-wave…
We report a neutron scattering study on the tetragonal compound Sr_2Cu_3O_4Cl_2, which has two-dimensional (2D) interpenetrating Cu_I and Cu_{II} subsystems, each forming a S=1/2 square lattice quantum Heisenberg antiferromagnet (SLQHA).…
Motivated by the observation of spatially anisotropic exchange constants in the iron pnictide materials, we study the spin-wave spectra of the $J_{1a}-J_{1b}-J_{2}$ Heisenberg models on a square-lattice with nearest neighbor exchange…
A spin-singlet ground state with a spin gap has been discovered in antiferromagnetic spin chain substances when the spin value is 1/2, 1 or 2. To find spin gap (singlet-triplet) excitations in spin-3/2 chain substances, we performed…
We report comprehensive thermodynamic and neutron scattering measurements on the $S$ = 3/2 antiferromagnet Cs$_2$CoI$_4$, a member of the thoroughly studied family of frustrated magnets Cs$_2MX_4$ ($M$ = Cu, Co, Ru, $X$ = Br, Cl, I, O).…
We investigate magnetic properties of a two-dimensional periodic structure with Ising spins and antiferromagnetic nearest neighbor interaction. The structure is topologically equivalent to the Archimedean (3,12^2) lattice. The ground state…