The spin-flop transition in the nearly one-dimensional antiferromagnets RbNiCl3 and CsNiCl3

A spin-flop transition has been observed in the ordered phase of the nearly one-dimensional antiferromagnets RbNiCl₃ and CsNiCl₃$\text{H}{}_{\mathrm{s?:;}}\text{= 19.3 ± 0.5}\text{and}\text{19.2 ± 0.3}\text{kG at}\text{1.65}\text{K}$, respectively). The transition involves flopping of the spins within the linear chains while the inter-chain order (the “triangular configuration”) is preserved. The low values of H_s?:; imply a small anisotropy parameter (D = -0.05 cm^-1).     

Low temperature magnetostriction studies in CsNiCl3

The forced magnetostriction of the linear-chain antiferromagnet CsNiCl₃ has been measured from 1.6 to 20K. For the applied field parallel to the c-axis the data below the Néel temperature T_N clearly show the effects of the spin-flop near 20 kG. Effects ascribed to domain realignment are observed below 5 kG for the field normal to the c-axis. In the paramagnetic phase above T_N the magnetostrictive behavior conforms to a simple model in which the intrachain exchange J is a function only of the c-parameter. The resulting partial Grüneisen parameter $\text{γ∥}{}^{\mathrm{m}}\text{=}\text{?d(?nJ)}\text{d(?nc)}$ is compared with that obtained from thermal expansion measurements.     

Nuclear spin lattice relaxation in the linear antiferromagnet CsNiCl3

Anisotropic effects have been found in the low temperature (< 10 K) nuclear spin lattice relaxation rates in the linear paramagnet CsNiCl₃ in a strong magnetic field (～ 60 kOe). The existence of a small single ion anisotropy term may be the cause of these effects.     

Thermal and magnetic studies of the nearly one-dimensional antiferromagnetic system CsNiBr3

Magnetic susceptibility, specific heat and ¹³³Cs magnetic resonance measurements in a single crystal of CsNiBr₃ are reported. The data reveal two magnetic transitions separating the paramagnetic phase from the antiferromagnetic ground state. At the higher transition temperature T_N2 = (14.25 ± 0.05)K a net magnetic moment is observed only along the hexagonal c-axis, while only below the lower transition temperature T_N1 = (11.75 ± 0.05)K a perpendicular component of the magnetic moment appears also. Above T_N2 CsNiBr₃ can be described as a one-dimensional antiferromagnet with intrachain exchange interaction $\text{J}\text{k}{}_{\mathrm{B}}\text{= ?(17.0 ± 0.2)}\text{K}$ and single-ion anisotropy constant $\text{D}\text{k}{}_{\mathrm{B}}\text{? ?1.5}\text{K}$. Below T_N1, the data are consistent with the non-colinear triangular structure of the Ni²⁺ moments proposed previously for the isomorphic crystal CsNiCl₃. A reduced value of the zero-temperature susceptibility over the classical value is found and atrributed to the zero point deviations.     

Effect of antiferromagnetic ordering on the optical transitions in MnF2

Two optical absorption bands (viz. C and F) in MnF₂, whose line positions are nearly temperature-independent above T_N = 67.3 K, are investigated for the effect of magnetic ordering. Both bands are blue-shifted by ΔE (≌90 cm^?1 for C and 120 cm^?1 for F at 10 K) and the lines show additional narrowing on cooling through T_N. It is found that ΔE varies as the sublattice lattice magnetization below T_N and nearly as the magnetic energy above T_N.     

Optically-detected antiferromagnetic resonance in KMnF3

Antiferromagnetic resonance has been detected optically by monitoring the intensity of light transmitted through a crystal of KMnF₃ at 2 K. At resonance, the intensity of the transmitted light decreases, implying that the absorption is enhanced by increases in magnon density.     

Incommensurate antiferromagnetic structures in NdIn3

Among the AuCu₃-type RIn₃ series where R is a rare earth, the NdIn₃ compound presents a complex magnetic phase diagram. In this compound, which orders antiferromagnetically at T_N = 5.9 K, three magnetic phases are separated by two sharp first-order transitions. The phase diagrams, determined for the main crystallographic directions, by magnetization measurements in fields up to 7 T show a strong dependence of the transition temperatures. In order to determine the actual magnetic structures in NdIn₃, a neutron diffraction experiment has been performed on a single crystal under magnetic field. It shows that the magnetic structures are collinear (single q) with the magnetic moments aligned along the fourfold axis. They clearly evidence the existence of two incommensurate phases with q = (1/2, 1/2, τ): for T_N T 5.5 K, τ₁ ≈ 0.037 2π/a and the structure is sine-wave modulated, for 5.5 K > T > 4.7 K, τ₂ = 0.017 2π/a and the structure squares up. Below 4.7 K the q = (1/2, 1/2, 0) commensurate structure is stabilized.     

Magnetic ordering in GdH3

In contrast to a previous report, GdH₃ is found to order antiferromagnetically at 1.8 K.     

Analysis of antiferromagnetic resonance in KNiF3

We have compared theoretical calculations of the temperature dependence of the antiferromagnetic resonance field for KNiF₃, a cubic crystal, with the experimental data obtained by other authors. We have discussed the applicability to the cubic case of Kittel's equations for a uniaxial system. We have used experimental values from the literature for the magnetic susceptibilities and anisotropy in the expression for the antiferromagnetic resonance field.     

Vibrational spectra of antiferromagnetic FeBO3

Transmission spectra of powdered ferric borate have been measured in the wave number region from 6000 cm^-1 to 30 cm^-1 at room and liq. N₂ temperatures. Eight absorption bands observed are assigned as three A_2u and five E_u phonon modes. Of those modes, the temperature dependence of the E_u mode ar 230 cm^-1 (300 K) and the A_2u mode at 277 cm^-1 (300 K) have been measured in the temperature range containing the Néel temperature. They do not show the influence of magnetic ordering.     

Nonlinear optical effects in antiferromagnetic KniF3

Frequency broadening and self-focusing of optical pulses are observed in antiferromagnetic KNiF₃ under intense pico- second laser excitation. Below the Néel temperature considerable enhancement of the frequency broadened intensity is observed which is attributed to the spin dependent part of the third order susceptibility.     

Two-exciton transition in the antiferromagnetic KNiF3 and K2NiF4

For the sharp band located at 31,200 cm^?1 in the three dimensional antiferromagnetic KNiF₃, the dependence of the oscillator strength on the Ni ion concentration and the stress-induced linear dichroic spectrum are studied. The polarization dependence of the corresponding band in the two dimensional antiferromagnetic K₂NiF₄ is also measured. The weak structure located at 30,780 cm^?1 is assigned as two-exciton transition, and the band at 31,200 cm^t?1 as a two-exciton transition accompanied with a T_1u phonon.     

Neutron diffraction study of antiferromagnetic TbIn3

Observations were on a polycrystalline sample using unpolarised neutrons, at temperatures of 4.2 K and 100 K. There is 1 1 0 antiferromagnetic ordering. The magnetic moment is 7.2±0.4 μ_B, with its direction close to that of the c-axis.     

Thermoelectric power of antiferromagnetic RIn3 compounds

The thermoelectric power (TEP) has been measured from 2.2 to 300 K for antiferromagnetic compounds, CeIn₃, NdIn₃, SmIn₃, GdIn₃ and (Ce_1−xLa_x)In₃ with x = 0.1 and 0.2. The effects of the antiferromagnetic order were observed on the TEP of these compounds below T_N. The observations are explained by the antiferromagnetic band gap formation theory proposed by Abel'skii.     

Negative magnetoresistance in the antiferromagnetic semimetal V1/3TaS2

Intercalated transition metal dichalcogenides(TMDCs) attract much attention due to their rich properties and potential applications. In this article, we grew successfully high-quality V_1/3TaS₂ crystals by a vapor transport method. We measured the magnetization, longitudinal resistivity ρ_xx(T, H), Hall resistivity ρ_xy(T, H), as well as performed calculations of the electronic band structure. It was found that V_1/3TaS₂ is an A-type ...     

59Co nuclear magnetic resonance in antiferromagnetic CsCoCl3

The ⁵⁹Co NMR in a CsCoCl₃ single crystal has been observed by the spin echo method at 4.2 K. The obtained spectrum is composed of seven distinct lines split by the nuclear-quadrupole interaction. The frequency of the central (± $\text{1}\text{2}$ ? ± $\text{1}\text{2}$) transition 502.08±0.05 MHz corresponds to the hyperfine field of 499.38 ± 0.05 kOe, which agrees well with the calculated value. Due to the interaction of the nucleus with the electronic moment induced by the external field, a shift as large as 18% was observed for the nuclear g-factor.     

Optical selection rules and magnon assignments for the low temperature magnetic spin structures of CsCoCl3 and CsNiCl3

The optical selection rules for excitons, magnons and exciton-magnon coupled modes are derived for the various magnetic phases of CsCoCl₃ and CsNiCl₃. For CsCoCl₃, these selection rules are used in conjunction with the energy levels calculated in the previous paper (I) to account for the sharp side bands observed in the optical spectrum. For CsNiCl₃, the discussion focuses on the utility of the selections rules to be used as a tool to distinguish phases, particularly in the region of the controversial intermediate phase.     

Spin-phonon interactions in cuprates

The parameter ζ of spin-phonon coupling is obtained through the analysis of the spin-wave dynamics of magnetic systems. It is shown that the parameter of spin-phonon coupling is greater, the greater the relative electron-ion potential g ₁, the smaller the exchange correlation radius r _c , and the smaller the mass M of ions that form a crystalline lattice.     

Antiferromagnetic ordering in the ytterbium aluminum perovskite YbAlO3

The antiferromagnetic ordering in YbAlO₃ at low temperatures has been studied. Susceptibility measurements are in agreement with certain features of a quasi one-dimensional Ising system. Neutron diffraction below 0.8 K suggests a structure of the type A_xG_y. The spontaneous magnetic moment at 100 mK compares well with the value from the ground state doublet and is in disagreement with Mössbauer results.