We have succeeded in synthesizing single crystals of a new organic radical 3-Cl-4-F-V [3-(3-chloro-4-fluorophenyl)-1,5-diphenylverdazyl]. Through the ab initio molecular orbital calculation and the analysis of the magnetic properties, this compound was confirmed to be the first experimental realization of an S=1/2 spin-ladder system with ferromagnetic leg interactions. The field-temperature phase diagram indicated that the ground state is situated very close to the quantum critical point. Furthermore, we found an unexpected field-induced successive phase transition, which possibly originates from the interplay of low dimensionality and frustration.

In situ X-ray and neutron powder diffraction were carried out for the La 4 MgNi 19 alloy sample, which was obtained by annealing under controlled Mg-vapor pressure and temperature. The sample contained five phases:

We have succeeded in synthesizing two types of new organic radical crystals 3-I-V [= 3-

We successfully synthesized the zinc-verdazyl complex [Zn(hfac)2]-(o-Py-V) [hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate; o-Py-V = 3-(2-pyridyl)-l,5-diphenylverdazyl], which is an ideal model compound with an S = j ferromagnetic-antiferromagnetic alternating Heisenberg chain (F-AF AHC). Ab initio molecularorbital (MO) calculations indicate that two dominant interactions 7F and 7AF form the S = | F-AF AHC in this compound. The magnetic susceptibility and magnetic specific heat of the compound exhibit thermally activated behavior below approximately 1 K. Furthermore, its magnetization curve is observed up to the saturation field and directly indicates a zero-field excitation gap of 0.5 T. These experimental results provide evidence for the existence of a Haldane gap. We successfully explain the results in terms of the S = \ F-AF AHC through quantum Monte Carlo calculations with |7AF/7 F| = 0.22. The ab initio MO calculations also indicate a weak AF interchain interaction 7' and that the coupled F-AF AHCs form a honeycomb lattice. The 7' dependence of the Haldane gap is calculated, and the actual value of 7' is determined to be less than 0.01|7F|.

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In this study, the change in internal lattice strain in an iron plate during tensile deformation was investigated by performing in situ measurements under applied force. The lattice strain was evaluated by neutron diffraction and Bragg‐edge transmission. The neutron diffraction results showed that the averaged 110 lattice strain along the direction perpendicular to the applied force was between −422 and −109 × 10−6. The position dependence of the lattice strain and the change in the distribution of elastic strain in an iron plate with notches during tensile deformation was obtained by Bragg‐edge transmission. It was also observed that, when the load increased over 30 kN, the area of plastic deformation increased around the positions of the notches.

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We report magnetization, specific heat, and NMR measurements of 3-Br-4-F-V [= 3-(3-bromo-4fluorophenyl)-1,5-diphenylverdazyl], strong-rung S=1/2 Heisenberg spin ladder with ferromagnetic leg interactions. We explain the magnetic and thermodynamic properties based on the strong-rung regime. Furthermore, we find a field-induced successive phase transition in the specific heat and the nuclear spin-lattice relaxation rate 1/T 1 . 19 F-NMR spectra for higher and lower temperature phases indicate partial magnetic order and incommensurate long-range order, respectively, evidencing the presence of frustration due to weak interladder couplings.