Solid state NMR characterisation of crystalline Na2OZrO2SiO2 phases

The NMR interactions of crystalline phases in the system Na₂O-ZrO₂-SiO₂ have been studied by a combination of static and magic angle spinning NMR methods for the first time. A full multinuclear (¹⁷O, ²³Na, ²⁹Si and ⁹¹Zr) approach has been employed that allows the phases to be clearly identified. NMR interactions such as ²⁹Si isotropic chemical shift correlate with the known structural units present. For ²³Na the different sites can often be distinguished on the basis of differing quadrupolar interactions.     

59Co NMR study of NdCo2, GdCo2, TbCo2 and HoCo2

We have observed the ⁵⁹Co spectra of the Laves phase Co compounds with Nd, Gd, Tb and Ho. We observe a spectrum consisting of a pair of lines for Nd, Tb and Ho compounds, because the Co sites are magnetically inequivalent in the presence of dipolar or pseudodipolar fields. For the heavy rare earth compounds, the magnitude of this splitting is comparable to the dipolar splitting produced by the neighboring spins, but for Nd it is much larger. The Nd compound is also anomalous in that the average hyperfine field is only 37.2 kOe while for the 3 heavy rare earth compounds it is about 60 kOe. The magnitude of the hyperfine field is discussed in terms of a simple model relating it to the cobalt moment and the rare earth spin.     

Spin polarization effect of Ni2 molecule

The density functional theory （DFT） method （b3p86） of Gaussian 03 is used to optimize the structure of the Ni2 molecule. The result shows that the ground state for the Ni2 molecule is a 5-multiple state, symbolizing a spin polarization effect existing in the Ni2 molecule, a transition metal molecule, but no spin pollution is found because the wavefunction of the ground state does not mingle with wavefunctions of higher-energy states. So the ground state for Ni2 molecule, which is a 5-multiple state, is indicative of spin polarization effect of the Ni2 molecule, that is, there exist 4 parallel spin electrons in Ni2 molecule. The number of non-conjugated electrons is greatest. These electrons occupy different spatial orbitals so that the energy of the Ni2 molecule is minimized. It can be concluded that the effect of parallel spin in the Ni2 molecule is larger than that of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell-Sorbie potential functions with the parameters of the ground state and other states of the Ni2 molecule are derived. The dissociation energy De for the ground state of the Ni2 molecule is 1.835 eV, equilibrium bond length Re is 0.2243 nm, vibration frequency we is 262.35 cm^-1. Its force constants f2, f3 and f4 are 1.1901 aJ.nm^-2, -5.8723 aJ.nm^-3, and 21.2505 aJ.nm^-4 respectively. The other spectroscopic data for the ground state of the Ni2 molecule ωeχe, Be and αe are 1.6315cm 2, 0.1141 cm^-1, and 8.0145× 10^-4 cm^-1 respectively.     

B NMR relaxation in superconductors: YRuB2 and LuRuB2

To investigate the electronic states in YRuB₂ and LuRuB₂, we have carried out ¹¹B NMR measurements. In the normal state, the spin-lattice relaxation rates 1/T₁'s in these compounds are proportional to the temperature T. 1/T₁'s show a small coherence peak just below the superconducting transition temperature T_c and decrease exponentially well below T_c. YRuB₂ and LuRuB₂ are found to be BCS superconductors with the energy gap 2Δ(0)=3.52 k_BT_c.     

Lyman transitions of high rovibrationally excited H2, HD and D2 molecules

Energies and probabilities of Lyman transitions of high rovibrationally excited H₂, HD and D₂ molecules have been measured and compared with calculations. The experimental results are obtained from laser-induced fluorescence spectra that have been recorded in the spectral range from 60 500 to 83 500 cm⁻¹, covering 2/3 of the hydrogen Lyman band system. The necessary vacuum-UV radiation is produced by stimulated anti-Stokes Raman scattering, providing a widely tunable radiation source with narrow spectral bandwidth to resolve single Lyman transitions. The highest internal energies of detected hydrogen isotopologues are close to the dissociation limit. This extends the available data base of Lyman transitions from and to higher rotational states (J > 10) of HD and D₂.     

Impurities detection by optical techniques in KH2PO4 crystals

In this paper we examine how optical techniques can be used for impurities (or defects) detection and identification in KH₂PO₄ (KDP) components. This is important in so far as some of these defects are responsible for a much weaker than expected Laser-Induced Damage Threshold (LIDT) in these materials, i.e. for a weaker resistance to a laser shot. KDP materials are investigated by photothermal deflection, fluorescence and photoexcitation with the aim of localizing and identifying the laser-induced damage precursors. The rapidly grown KDP crystals are shown to be heterogeneous from the absorption, fluorescence and composition point of view. Impurities concentrations are measured directly by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) and tentatively correlated to some optical characteristics and to the LIDT of KDP materials.     

Spin polarization effect for Fe2 molecule

This paper uses the density functional theory （DFT）（B3p86） of Gaussian03 to optimize the structure of Fe2 molecule. The result shows that the ground state for Fe2 molecule is a 9-multiple state, which shows spin polarization effect of Fe2 molecule of transition metal elements for the first time. Meanwhile, we have not found any spin pollution because the wavefunction of the ground state does not mingle with wavefunctions with higher energy states. So, that the ground state for Fe2 molecule is a 9-multiple state is indicative of the spin polarization effect of Fe2 molecule of transition metal elements. That is, there exist 8 parallel spin electrons. The non-conjugated electron is greatest in number. These electrons occupy different spacious tracks, so that the energy of the Fe2 molecule is minimized. It can be concluded that the effect of parallel spin of the Fe2 molecule is laFger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell Sorbie potential functions with the parameters for the ground state and other states of Fe2 molecule are derived. Dissociation energy De for the ground state of Fe2 molecule is 2.8586ev, equilibrium bond length Re is 0.2124nm, vibration frequency we is 336.38 cm^-1. Its force constants f2, f3, and f4 are 1.8615aJ.nm^-2, -8.6704aJ.nm^-3, 29.1676aj.nm^-4 respectively. The other spectroscopic data for the ground state of Fe2 molecule weXe, Be, αe are 1.5461 cm^-1, 0.1339cm^-1, 7.3428× 10^-4 cm^-1 respectively.     

Spin polarization effect for molecule Ta2

Density functional theory （DFT） （B3p86） has been used to optimize the structure of the molecule Ta2. The result shows that the ground state of molecule Ta2 is a 7-multiple state and its electronic configuration is ^7∑u^＋, which shows the spin polarization effect for molecule Ta2 of transition metal elements for the first time. Meanwhile, spin pollution has not been found because the wavefunction of the ground state does not mix with those of higher states. So, the fact that the ground state of molecule Ta2 is a 7-multiple state indicates a spin polarization effect of molecule Ta2 of the transition metal elements, i.e. there exist 6 parallel spin electrons and the non-conjugated electrons are greatest in number. These electrons occupy different space orbitals so that the energy of molecule Ta2 is minimized. It can be concluded that the effect of parallel spin of the molecule Ta2 is larger than the effect of the conjugated molecule, which is obviously related to the effect of d-electron delocalization. In addition, the Murrell-Sorbie potential functions with parameters for the ground state ^7∑u^＋ and other states of the molecule Ta2 are derived. The dissociation energy De, equilibrium bond length Re and vibration frequency we for the ground state of molecule Ta2 are 4.5513eV, 0.2433nm and 173.06cm^-1, respectively. Its force constants f2, f3 and f4 are 1.5965×10^2aJ.nm^-2, -6.4722×10^3aJ·nm^-3 and 29.4851×10^4aJ·nm^-4, respectively. Other spectroscopic data we xe, Be and αe for the ground state of Ta2 are 0.2078cm^-1, 0.0315 cm^-1 and 0.7858×10^-4 cm^-1, respectively.     

Spin polarization effect for Cr2 molecule

Density functional theory （DFT） （B3P86） of Gaussian 03 has been used to optimize the structure of the Cr2 molecule, a transition metal element molecule. The result shows that the ground state for the Cr2 molecule is a 13- multiple state, indicating that there exists a spin polarization effect in the Cr2 molecule. Meanwhile, we have not found any spin pollution because the wave function of the ground state does not mingle with wave functions of higher-energy states. So the ground state for Cr2 molecule being a 13-multiple state is indicative of spin polarization effect of the Cr2 molecule among transition metal elements, that is, there are 12 parallel spin electrons in the Cr2 molecule. The number of non-conjugated electrons is greatest. These electrons occupy different spatial orbitals so that the energy of the Cr2 molecule is minimized. It can be concluded that the effect of parallel spin in the Cr2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell Sorbie potential functions with the parameters for the ground state and other states of the Cr2 molecule are derived. The dissociation energy De for the ground state of the Cr2 molecule is 0.1034eV, equilibrium bond length Re is 0.3396 nm, and vibration frequency we is 73.81cm^-1. Its force constants f2, f3 and f4 are 0.0835, -0.2831 and 0.3535 aJ. nm^-4 respectively. The other spectroscopic data for the ground state of the Cr2 molecule ωeχe, Be and αe are 1.2105, 0.0562 and 7.2938 x 10^-4cm^-1 respectively.     

Spin polarization effect for Mn2 molecule

The density functional theory method （DFT） （b3p86） of Gaussian 03 has been used to optimize the structure of the Mn2 molecule. The result shows that the ground state of the Mn2 molecule is an 11-multiple state, indicating a spin polarization effect in the Mn2 molecule, a transition metal element molecule. Meanwhile, we have not found any spin pollution because the wavefunction of the ground state does not mingle with wavefunctions of higher-energy states. So the ground state for Mn2 molecule being of an 11-multiple state is the indicative of spin polarization effect of the Mn2 molecule among those in the transition metal elements： that is, there are 10 parallel spin electrons in a Mn2 molecule. The number of non-conjugated electrons is the greatest. These electrons occupy different spacious orbitals so that the energy of the Mn2 molecule is minimized. It can be concluded that the effect of parallel spin in the Mn2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell-Sorbie potential functions with the parameters for the ground state and other states of the Mn2 molecule are derived. The dissociation energy De for the ground state of the Mn2 molecule is 1.4477 eV, equilibrium bond length Re is 0.2506 nm, vibration frequency ωe is 211.51 cm^-1. Its force constants f2, f3, and f4 are 0.7240 aJ·nm-2, -3.35574 aJ·nm^-3, 11.4813 aJ·nm^-4 respectively. The other spectroscopic data for the ground state of the Mn2 molecule ωeχe, Be, αe are 1.5301 cm^-1, 0.0978 cm^-1, 7.7825×10^-4 cm^-1 respectively.     

Spin polarization effect for Co2 molecule

The density functional theory (DFT)(b3p86) of Gaussian 03 has been used to optimize the structure of the Co$_{2}$ molecule, a transition metal element molecule. The result shows that the ground state for the Co$_{2}$ molecule is a 7-multiple state, indicating a spin polarization effect in the Co$_{2}$ molecule. Meanwhile, we have not found any spin pollution because the wavefunction of the ground state is not mingled with wavefunctions of higher-energy states. So for the ground state of Co$_{2}$ molecule to be a 7-multiple state is the indicative of spin polarization effect of the Co$_{2}$ molecule, that is, there exist 6 parallel spin electrons in a Co$_{2}$ molecule. The number of non-conjugated electrons is the greatest. These electrons occupy different spacial orbitals so that the energy of the Co$_{2}$ molecule is minimized. It can be concluded that the effect of parallel spin in the Co$_{2}$ molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell--Sorbie potential functions with the parameters for the ground state and the other states of the Co$_{2}$ molecule are derived. The dissociation energy $De$ for the ground state of Co$_{2}$ molecule is 4.0489eV, equilibrium bond length $R_{\rm e}$ is 0.2061~nm, and vibration frequency $\omega _\e $ is 378.13~cm$^{ - 1}$. Its diatomic molecule force constants $f_2$, $f_3$, and $f_4$ are 2.4824~aJ$\cdot$nm$^{ - 2}$, -7.3451~aJ$\cdot$nm$^{ - 3}$, and 11.2222~aJ$\cdot$nm$^{ - 4 }$respectively(1~aJ=$10^{-18}$~J). The other spectroscopic data for the ground state of Co$_{2}$ molecule $\omega_{\e}\chi _{\e}$, $B_{\e}$, and $\alpha_{\e}$ are 0.7202~cm$^{-1}$, 0.1347~cm$^{-1 }$, and 2.9120$\times $ 10$^{-1}$~cm$^{-1}$ respectively. And $\omega_{\e}\chi _{\e}$ is the non-syntonic part of frequency, $B_{\e}$ is the rotational constant, $\alpha_{\e}$ is revised constant of rotational constant for non-rigid part of Co$_2$ molecule.     

Spin polarization effect for Os2 molecule

Density functional Theory （DFT） （B3p86） of Gaussian03 has been used to optimize the structure of Os2 molecule. The result shows that the ground state for Os2 molecule is 9-multiple state and its electronic configuration is ^9∑^＋g, which shows spin polarization effect of Os2 molecule of transition metal elements for the first time. Meanwhile, we have not found any spin pollution because the wavefunction of the ground state does not mingle with wavefunctions with higher energy states. So, the fact that the ground state for Os2 molecule is a 9-multiple state is indicative of spin polarization effect of Os2 molecule of transition metal elements. That is, there exist 8 parallel spin electrons. The non-conjugated electron is greatest in number. These electrons occupy different spacious tracks, so that the energy of Os2 molecule is minimized. It can be concluded that the effect of parallel spin of Os2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell-Sorbie potential functions with the parameters for the ground state ^9∑^＋g and other states of Os2 molecule are derived. Dissociation energy De for the ground state of Os2 molecule is 3.3971eV, equilibrium bond length Re is 0.2403nm, vibration frequency ωe is 235.32cm^-1. Its force constants f2, f3, and f4 are 3.1032×10^2aJ·nm^-2, -14.3425×10^3aJ·nm^-3 and 50.5792×10^4aJ·nm^-4 respectively. The other spectroscopic data for the ground state of Os2 molecule ωexe, Be and ae are 0.4277cm^- 1, 0.0307cm^- 1 and 0.6491 × 10^-4cm^-1 respectively.     

Spin polarization effect for Tc2 molecule

Density functional method (DFT) (B3p86) of Gaussian98 has been used to optimize the structure of the Tc_2 molecule. The result shows that the ground state for Tc_2 molecule is an 11-multiple state and its electronic configuration is {}^{11}Σ_g^-, which shows the spin polarization effect of Tc_2 molecule of a transition metal element for the first time. Meanwhile, we have not found any spin pollution because the wavefunction of the ground state does not mingle with wavefunctions of higher energy states. So, that the ground state for Tc_2 molecule is an 11-multiple state is indicative of the spin polarization effect of Tc_2 molecule of a transition metal element: that is, there exist 10 parallel spin electrons. The non-conjugated electron is greatest in number. These electrons occupy different spacious tracks, so that the energy of Tc_2 molecule is minimized. It can be concluded that the effect of parallel spin of the Tc_2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell--Sorbie potential functions with the parameters for the ground state {}^{11}Σ_g^- and other states of Tc_2 molecule are derived. Dissociation energy D_e for the ground state of T_{c2} molecule is 2.266eV, equilibrium bond length R_e is 0.2841nm, vibration frequency ω_e is 178.52cm^{-1}. Its force constants f_2, f_3, and f_4 are 0.9200aJ·nm^{-2}, --3.5700aJ·nm^{-3}, 11.2748aJ·nm^{-4} respectively. The other spectroscopic data for the ground state of Tc_2 molecule ω_eχ_e, B_e, α_e are 0.5523cm^{-1}, 0.0426cm^{-1}, 1.6331×10^{-4}cm^{-1} respectively.     

Spin fluctuations in the paramegnetic state of YMn2

Polarisation neutron diffusion and polarisation analysis has been performed on YMn₂ in the paramagnetic state up to 3T_N. Results revealed an important scattering at all temperatures, it remains strongly enhanced about the staggered antiferromagnetic wave vectors. Furthermore, the amplitude of the diffusion increases with temperature.     

Spin pumping at the Co2 FeAl0.5Si0.5/Pt interface

Spin pumping at the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces has been studied by ferromagnetic resonance technology(FMR). The spin mixing conductance of the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces was determined to be 3.7×1019m 2and 2.1×1019m 2 by comparing the Gilbert damping in a Co2FeAl0.5Si0.5single film, Co2FeAl0.5Si0.5/Pt bilayer film and a Pt/Co2FeAl0.5Si0.5/Pt trilayer film. Spin pumping is more efficient in the Co2FeAl0.5Si0.5/Pt bilayer film than in permalloy/Pt bilayer film.     

Spin glass properties of vanadium diluted in Ti2O3

The initial magnetic susceptibility χ_r, the thermoremanent and isothermal remanent magnetizations have been measured below 10 K on single crystals of (Ti_1?xV_x)₂O₃ for x = 0.03, 0.05 and 0.07. The data clearly show a spin glass behaviour, with peaks in the curve χ_r(T). These results are related to the anomaly in the low temperature specific heat of these compounds, reported elsewhere. It is shown that this anomaly is mainly due to spin glass properties and only partly to electronic properties. This leads to a reinterpretation of the mechanism by which V in Ti₂O₃ induces the metallic phase and at the same time carries a magnetic moment.     

Al NMR studies of NpPd5Al2

We present ²⁷Al NMR studies for a single crystal of the Np-based superconductor NpPd₅Al₂. We have observed a five-line ²⁷Al NMR spectrum with a center line and four satellite lines separated by first-order nuclear quadrupole splittings. The Knight shift clearly drops below T_c. The temperature dependence of the ²⁷Al nuclear spin-lattice relaxation rate shows no coherence peak below T_c, indicating that NpPd₅Al₂ is an unconventional superconductor with an anisotropic gap. The analysis of the present NMR data provides evidence for strong-coupling d-wave superconductivity in NpPd₅Al₂.     

Spin frozen in the Kondo-lattice compound: CeCuSi2

In this paper, we present the experimental results of X-ray powder diffraction, electrical resistivity, magnetic susceptibility, and specific-heat measurements as well as Ce-L_III-edge X-ray absorption spectrum of the Ce-based intermetallic compound CeCuSi₂. The results revealed that CeCuSi₂ is a Kondo-lattice compound with no superconducting or magnetic-phase transition above 0.4 K. In addition, we found spin-glass behavior in the DC susceptibility measurements. The AC susceptibility measurements and the magnetic entropy calculation also confirm the presence of the spin-glass phase. The possible formation mechanism for the spin-frozen state is also discussed in this paper.     

Spin gap in quasi-one-dimensional S=3/2 antiferromagnet CoTi2O5

Quasi-one-dimensional(1D) antiferromagnets are known to display intriguing phenomena especially when there is a spin gap in their spin-excitation spectra. Here we demonstrate that a spin gap exists in the quasi-1D Heisenberg antiferromagnet CoTi₂O₅ with highly ordered Co²⁺/Ti⁴⁺ occupation, in which the Co²⁺ ions with S = 3/2 form a 1D spin chain along the a-axis. CoTi₂O₅ undergoes an antiferromagnetic transition at T