Broken axisymmetry phase of a spin-1 ferromagnetic Bose-Einstein condensate

A spin-1 ferromagnetic Bose-Einstein condensate subject to a certain magnetic field exhibits a broken-axisymmetry phase in which the magnetization tilts against the applied magnetic field due to the competition between ferromagnetism and linear and quadratic Zeeman effects. The Bogoliubov analysis shows that in this phase two Goldstone modes associated with U(1) and SO(2) symmetry breakings exist, in which phonons and magnons are coupled to restore the two broken symmetries.Comment: 11 pages, 6 figure

Glassy dynamics in thin films of polystyrene

Glassy dynamics was investigated for thin films of atactic polystyrene by complex electric capacitance measurements using dielectric relaxation spectroscopy. During the isothermal aging process the real part of the electric capacitance increased with time, whereas the imaginary part decreased with time. It follows that the aging time dependences of real and imaginary parts of the electric capacitance were primarily associated with change in volume (film thickness) and dielectric permittivity, respectively. Further, dielectric permittivity showed memory and rejuvenation effects in a similar manner to those observed for poly(methyl methacrylate) thin films. On the other hand, volume did not show a strong rejuvenation effect.Comment: 7 pages, 7 figures. Phys. Rev. E (in press

A rectangular Ni-Fe cluster with unusual cyanide bridges

An asymmetric polycyanide iron complex, K2[Fe III(L1)(CN)4](MeOH) (HL1 = 2,2′-(1H-pyrazole-3,5- diyl)bis-pyridine), was synthesized and its complexation compatibility with nickel ions was examined. Two kinds of enantiomeric nickel-iron squares were obtained in the presence of a chiral bidentate capping ligand. The compounds display unusual cyanide bridge geometry and have ferromagnetic interactions between nickel and iron ions. © 2013 The Royal Society of Chemistry

Novel Magnetic and Thermodynamic Properties of Thiospinel Compound CuCrZrS4_{4}

We have carried out dc magnetic susceptibility, magnetization and specific heat measurements on thiospinel CuCrZrS$_{4}$. Below $T_{\rm C}^{*} =$ 58 K, dc magnetic susceptibility and magnetization data show ferromagnetic behavior with a small spontaneous magnetization 0.27 $\mu_{\rm B}/$f. u.. In dc magnetic susceptibility, large and weak irreversibilities are observed below $T_{\rm f} =$ 6 K and in the range $T_{\rm f}< T < T_{\rm C}^{*}$ respectively. We found that there is no anomaly as a peak or step in the specific heat at $T_{\rm C}^{*}$.Comment: 11 pages, 4 figure

Hard to "tune in": neural mechanisms of live face-to-face interaction with high-functioning autistic spectrum disorder

Persons with autism spectrum disorders (ASD) are known to have difficulty in eye contact (EC). This may make it difficult for their partners during face to face communication with them. To elucidate the neural substrates of live inter-subject interaction of ASD patients and normal subjects, we conducted hyper-scanning functional MRI with 21 subjects with autistic spectrum disorder (ASD) paired with typically-developed (normal) subjects, and with 19 pairs of normal subjects as a control. Baseline EC was maintained while subjects performed real-time joint-attention task. The task-related effects were modeled out, and inter-individual correlation analysis was performed on the residual time-course data. ASD-Normal pairs were less accurate at detecting gaze direction than Normal-Normal pairs. Performance was impaired both in ASD subjects and in their normal partners. The left occipital pole (OP) activation by gaze processing was reduced in ASD subjects, suggesting that deterioration of eye-cue detection in ASD is related to impairment of early visual processing of gaze. On the other hand, their normal partners showed greater activity in the bilateral occipital cortex and the right prefrontal area, indicating a compensatory workload. Inter-brain coherence in the right IFG that was observed in the Normal-Normal pairs (Saito et al., 2010) during EC diminished in ASD-Normal pairs. Intra-brain functional connectivity between the right IFG and right superior temporal sulcus (STS) in normal subjects paired with ASD subjects was reduced compared with in Normal-Normal pairs. This functional connectivity was positively correlated with performance of the normal partners on the eye-cue detection. Considering the integrative role of the right STS in gaze processing, inter-subject synchronization during EC may be a prerequisite for eye cue detection by the normal partner

Systematic perturbation approach for a dynamical scaling law in a kinetically constrained spin model

The dynamical behaviours of a kinetically constrained spin model (Fredrickson-Andersen model) on a Bethe lattice are investigated by a perturbation analysis that provides exact final states above the nonergodic transition point. It is observed that the time-dependent solutions of the derived dynamical systems obtained by the perturbation analysis become systematically closer to the results obtained by Monte Carlo simulations as the order of a perturbation series is increased. This systematic perturbation analysis also clarifies the existence of a dynamical scaling law, which provides a implication for a universal relation between a size scale and a time scale near the nonergodic transition.Comment: 17 pages, 7 figures, v2; results have been refined, v3; A figure has been modified, v4; results have been more refine

Carboxylic acid functionalized spin-crossover iron(II) grids for tunable switching and hybrid electrode fabrication

Two carboxyl-substituted iron(II) grids, one protonated, [Fe4(HL)4](BF4)4·4MeCN·AcOEt (1), and the other deprotonated, [Fe4(L)4]·DMSO·EtOH (2), where H2L = 4-{4,5-bis[6-(3,5-dimethylpyrazol-1-yl)pyrid-2-yl]-1H-imidazol-2-yl}benzoic acid, were synthesized. Single-crystal X-ray structure analyses reveal that both complexes have a tetranuclear [2 × 2] grid structure. 1 formed one-dimensional chains through intermolecular hydrogen bonds between the carboxylic acid units of neighboring grids, while 2 formed two-dimensional layers stabilized by π–π-stacking interactions. 1 showed spin transition between the 3HS-1LS and 1.5HS-2.5LS states around 200 K, while 2 showed spin-crossover between the 4LS and 2LS-2HS states above 300 K. A modified indium–tin oxide (ITO) electrode was fabricated by soaking the ITO in a solution of 1. The resultant electrode showed reversible redox waves attributed to the original redox processes of iron(II)/iron(III)

Superconducting gap function in the organic superconductor (TMTSF)2ClO4 with anion ordering; First-principles calculations and quasiclassical analysis for angle-resolved heat capacity

We calculate angle-dependent heat capacity in a low magnetic field range on the basis of Kramer-Pesch approximation together with an electronic structure obtained by first-principles calculations to determine a superconducting gap function of (TMTSF)2ClO4 through its comparisons with experiments. The present comparative studies reveal that a nodal d-wave gap function consistently explains the experimental results for (TMTSF)2ClO4. Especially, it is emphasized that the observed unusual axis-asymmetry of the angle-dependence eliminates the possibility of s-wave and node-less d-wave functions. It is also found that the directional ordering of ClO4 anions does not have any significant effects on the Fermi surface structure contrary to the previous modelings since the two Fermi surfaces obtained by the band calculations almost cross within the present full accuracy in first-principles calculations.Comment: 8 pages, 11 figures, Accepted in Phys. Rev.