Transition metal dichalcogenides are studied due to the possibility of creating nanoscale semiconductor devices, as well as fundamental issues of magnetic ordering. We researched the crystal structure and magnetic properties of niobium dichalcogenide Mn0.30NbS2. The results of the X-ray study showed the possible existence of an intermediate 23a0·23a0 structure between the “basic” superstructures. Also, two local maximums were found in the temperature dependence of the dynamic magnetic susceptibility. These features can indirectly confirm the presence of a transition superstructure and reflect the two-step nature of the magnetic ordering.

This paper presents the results of a study of the Mn1/3NbS2 magnet using the 55Mn nuclear magnetic resonance method in the absence of an external magnetic field. The results show that, in a magnetically ordered region, the manganese ions are in the same state with a valence of +3. At a temperature T = 4.2 K, the magnitude of the hyperfine field at the nucleus, hst = 448(6) kOe, and the mean magnetic moment of manganese, μ = 3.6 µB, are determined.

The Cr 1/3 NbS 2 magnet is studied by nuclear magnetic resonance (NMR) at 53 Cr nuclei in a zero applied magnetic field. The following two frequency ranges are distinguished in the 53 Cr NMR spectrum at T = 4.2 K: ν 1 = 64–68 MHz and ν 2 = 49–51 MHz. They can be related to two valence states of chromium ions, namely, Cr 4+ and Cr 3+ . The components of the electric field gradient, the hyperfine fields, and the magnetic moment at chromium atoms are determined. The NMR data demonstrate that the magnetic moments of chromium lie in plane ab and form a magnetic structure consisting of regions with a helicoidal magnetic order and regions where this order is broken.

We have used time-resolved scanning Kerr microscopy and micromagnetic simulations to demonstrate that, when driven by the spatially uniform microwave field, the edges of patterned magnetic samples represent both efficient and highly tunable sources of propagating spin waves. The excitation is due to the local enhancement of the resonance frequency induced by the non-uniform dynamic demagnetizing field generated by precessing magnetization aligned with the edges. Our findings represent a crucial step forward in the design of nanoscale spin-wave sources for magnonic architectures and are also highly relevant to the understanding and interpretation of magnetization dynamics driven by spatially uniform magnetic fields in patterned magnetic samples.

Starting from the general topic and fundamentals of magnonics, we discuss and provide demonstrations of exciting new physics and technological opportunities associated with the graded magnonic index and spin wave Fano resonances, highlighting them as the next big thing in magnonics research.

The crystal structure of a disordered form of Cr_1/3NbS_2 has been characterized using diffraction and inelastic scattering of synchrotron radiation. In contrast to the previously reported symmetry (P6_322), the crystal can be described by a regular twinning of an average P6_3 structure with three disordered positions of the Cr ions. Short-range correlations of the occupational disorder result in a quite intense and structured diffuse scattering; a static nature of the disorder was unambiguously attributed by the inelastic x-ray scattering. The diffuse scattering has been modeled using a reverse Monte-Carlo algorithm assuming a disorder of the Cr sub-lattice only. The observed correlated disorder of the Cr sub-lattice reduces the temperature of the magnetic ordering from 130 K to 88 K and drastically modifies the field dependence of the magnetization as it is evidenced by the SQUID magnetometery. We conclude, that in contrast to the helicoidal spin structure assumed for P6_322 form, the compound under study is ferromagnetically ordered with a pronounced in-plane anisotropy.

A new representative of calix[4]arene-containing tetranuclear manganese complexes of [Mn2IIIMn2II] type with 2,2′-dipyridyl bidentate ligand coordinated in the equatorial plane of the complex (II) has been obtained. The complex is crystallized in monoclinic space group P21/c (a=14.9402(7)Å, b=32.816(1)Å, c=21.595(1)Å, β=106.888(4)). Its magnetic properties have been studied by the method of SQUID magnetometry. The substitution of a peripheral ligand was shown to influence substantially on the structure of the central fragment of the metal complex, and, hence, on the magnetic properties. Quantum-chemical calculations were performed for this complex and for the similar calix[4]arene-containing manganese complex with pyridine ligand (I). The influence of peripheral environment on the magnetic properties of tetranuclear manganese skeleton was elucidated for both complexes.

We report on a nanoscaled thermocouple (ThC) as a temperature sensor of a highly sensitive bolometer for probing the dissipative damping of spin dynamics in nanosized Permalloy (Py) stripes. The Au-Pd ThC based device is fabricated by standard electron beam lithography on a 200 nm silicon nitride membrane to minimize heat dissipation through the substrate. We show that this thermal sensor allows not only measurements of the temperature change on the order of a few mK due to the uniform resonant microwave (MW) absorption by the Py stripe but also detection of standing spin waves of different mode numbers. Using a 3D finite element method, we estimate the absorbed MW power by the stripe in resonance and prove the necessity of using substrates with an extremely low heat dissipation like a silicon nitride membrane for successful thermal detection. The voltage responsivity and the noise equivalent power for the ThC-based bolometer are equal to 15 V W−1 and 3 nW Hz−1/2, respectively. The ThC device offers a magnetic resonance response of 1 nV/(μB W) corresponding to a sensitivity of 109 spins and a temperature resolution of 300 μK under vacuum conditions.

Contributions of homogeneous and Goldstone modes of the spin precession were distinguished in FMR spectra of Cr 1/3 NbS 2 chiral helimagnet. The resonance field of homogeneous mode is determined by uniaxial magnetic anisotropy. The resonance field of Goldstone mode is determined by six-fold anisotropy in basal plane. For the first time, it has been shown experimentally that effective excitation of Goldstone mode is realized only when microwave magnetic field vector h is perpendicular to wave vector of magnetic structure Q .

New tetranitrosyl binuclear iron complex [Fe-2(SC7H5N4)(2)(NO)(4)] (I) has been synthesized by interaction of aqueous solutions of anionic salts [Fe(S2O3)(2)(NO)(2)](3-) and [SC7H5N4](-). The latter one was synthesized by reduction of bis-(1-phenyl-1H-tetrazole-5-y1) disulfide with hydrazine hydrate in ethanol at T= 25 degrees C. Molecular and crystalline structure of I was determined by X-ray analysis; the complex has binuclear structure of "mu-SCN" type with similar to 4.02 angstrom between the iron atoms. Shortened O center dot center dot center dot O contacts (2.81 angstrom) between the NO groups of similar type are observed. Parameters of M6ssbauer spectrum for I are: isomer shift delta(Fe) = 0.311(1) mm/s, quadrupole splitting Delta E-Q = 1.044(1) mm/s, line width Gamma = 0.267(1) mm/s at 85 K. From SQUID magnetometry data, the temperature and field dependences of the magnetic moment of I are well described in the frame of a simple model of binuclear iron complex with magnetic centers S-1 = S-2 = 1/2. In solution, binuclear structure of the complex remains, though the NO groups are non-equivalent. For solutions of I five-line hyperfine structure of spectrum (HFS) is observed, g-factor = 2.03. For polycrystals of!, no HFS was observed due to averaged exchange interaction between the electron spins of adjacent complexes. In polycrystals of I, the number of spins per one binuclear complex is <2, this being the evidence of antiferromagnetic exchange interaction of unpaired electrons of two iron atoms. The average number of spins in crystals (0.65) and solutions (0.55) are close. The maximum amount of NO generated by 1 in 1% dimethylsulfoxide (DMSO) aqueous solution is similar to 13.8 nM, it halves in 8 min after decomposition starts, and reaches similar to 3.8 nM in anaerobic conditions at T=25 degrees C, pH 7.0. This is due, according to quantum-chemical calculations, to the presence of a more stable Fe-NO bond in I than in its isostructural analog - nitrosyl iron complex with 1-methyltetrazole-5-yl (II). (C) 2013 Elsevier B.V. All rights reserved.

We describe herein the synthesis of (rac)- or enantiopure (S)-(-)-(2-MeBu)N(Pr)₂MeI ammonium salts. These racemic and enantiopure ammonium salts were used as cationic templates to obtain new two-dimensional (2D) ferromagnets [(rac)-(2-MeBu)N(Pr)₂Me][MnCr(C₂O₄)₃] and [(S)-(-)-(2-MeBu)N(Pr)₂Me][ΔMnΛ nCr(C₂O₄)₃]. The absolute configuration of the hexacoordinated Cr(III) metallic ion in the enantiopure 2D network was determined by a circular dichroism measurement. The structure of [(2-MeBu)N(Pr)₂Me][MnCr(C₂O₄)₃], established by single crystal X-ray diffraction, belongs to the chiral P63 space group. According to direct current (dc) magnetic measurements, these compounds are ferrromagnets with a temperature Tc = 6°K.

The high-frequency spin excitations in the Cr 1/3 NbS 2 helical magnet have been investigated. The contributions of the uniform and Goldstone modes of the spin precession have been determined. It has been shown that the resonant field of the uniform mode is determined by the uniaxial magnetocrystalline anisotropy. Final values of the energy and the resonant field of the Goldstone mode are determined by the sixth-order magnetocrystalline anisotropy in the basal plane.

A new representative of calix[4]arene-containing tetranuclear manganese complexes of the [MnII 2MnIII 2] type was obtained. According to the data of magnetoochemical studies, the complex exhibits properties of molecular magnet at the temperature below 5 K. Parameters of the exchange interaction and the activation energy were determined. The influence of the peripheral environment on the magnetic properties of the tetranuclear manganese framework in the structure of the complex was revealed.

A sequence of maxima of microwave absorption has been found in the ferromagnetic resonance (FMR) spectra of the chiral molecular ferrimagnet [Mn{(R/S)-pn}] 2 [Mn{(R/S)-pn} 2 (H 2 O)][Cr(CN) 6 ] 2 , which, as is shown, corresponds to the spin-soliton resonance. It has been established that this sequence corresponds to an incommensurate magnetic structure induced by the competition between the symmetric and antisymmetric exchange interactions. On the basis of the FMR spectra and their dependence on the temperature, the parameters of the modulated magnetic structure have been estimated.

In this paper the contributions of switching, slide, creep and Debye relaxation modes of the domain wall dynamics to the low-frequency magnetic properties of chiral and racemic [MnII(HL-pn)(H2O)][MnIII(CN)6]2H2O molecular ferrimagnets were distinguished.

In this paper we distinguish the contributions of switching, slide, creep and Debye relaxation modes of the domain wall dynamics to the low-frequency magnetic properties of chiral and racemic [MnII(HL-pn)(H2O)][MnIII(CN)6]·2H2O molecular ferrimagnets. We demonstrate that crystal and spin chirality affects the characteristic transition temperatures between different modes. In chiral crystals, transitions to the creep and Debye relaxation modes were observed at T = 7 K and 5 K, whereas in racemic crystals the same transitions occurred at higher temperatures T = 13 K and 9 K, respectively. Difference of the Peierls relief in chiral and racemic crystals is a possible reason of the chirality effect on the domain walls dynamics.