[en] The magnetic phase diagram of the antiferromagnet DyAg (T_N=56 K, T₂=49 K and T₁=46.5 K) has been investigated by measurements of the magnetization up to 54 T, the magnetic susceptibility and the specific heat in applied fields along the [1 0 0], [1 1 0] and [1 1 1] axes. At low temperatures below T₁, the magnetization along the [1 1 1] axis reaches saturation after four metamagnetic jumps with saturated moment of 9.7μ_B/Dy. The obtained phase diagrams below 40 K are well consistent with previous results for all directions. Above 40 K, on the other hand, the present results reveal the existence of some new phases in the proximity region of T_N. The magnetic structures are examined theoretically for several magnetic phases to clarify actual models for this material

[en] Anisotropic electrical resistivity and magnetic susceptibility are measured on single crystals of Sr_14-xA_xCu₂₄O₄₁ (A = Ca, Y). This material contains two-leg antiferromagnetic spin ladders that are progressively doped with hole carriers upon Ca substitution and thus determine the charge-transport properties. Application of hydrostatic pressure to this system has an effect similar to Ca substitution, increasing the hole density in the ladders. The resistivity shows remarkable anisotropy, indicative of a one-dimensional electronic state. copyright 1997 The American Physical Society

[en] The condition for the rearrangement of martensite variant (RMV) by magnetic field has been studied quantitatively in a wide temperature range for two types of alloys: a Ni₂MnGa with 10M martensite and a Ni_2.02Mn_1.09Ga_0.89 with 14M martensite. The RMV by magnetic field occurs at any temperature for the 10M martenste but only in a limited temperature range for the 14M martensite. The magnetic field at which the RMV starts to occur, H_s, increases with decreasing temperature for both alloys. The condition for the RMV by magnetic field is explained by two shear stresses: the magnetic shear stress acting across twinning plane t_mag (which is evaluated as the difference in magnetic energy between variants divided by twinning shear) and the shear stress required for twinning plane movement t_req. That is, the RMV by magnetic field starts to occur when t_mag exceeds t_req regardless of temperature and structure of martensite

[en] Lightly doped La_2-xSr_xCuO₄ in the so-called ''insulating'' spin-glass phase has been studied by angle-resolved photoemission spectroscopy. A quasi-particle (QP) peak crossing the Fermi level has been observed in the node direction of the d-wave superconducting gap, forming an ''arc'' of Fermi surface consistent with the recently observed metallic transport behavior at high temperatures of lightly doped materials. The spectral weight of the nodal QP smoothly increases with hole doping, corresponding to the n∼x behavior of the carrier number in the underdoped and lightly doped regions

[en] The effect of long term exposure to high magnetic fields at cryogenic temperatures on the microstructural stability of austenitic stainless steel was investigated. Three samples of SUS316 were prepared. One was as-machined, the second was solution heat-treated, and the last was solution heat-treated followed by a sensitization heat treatment. The samples were attached to the helical coil cover of the Large Helical Device, which is a large plasma experimental device operating with a superconducting magnet system. The maximum magnetic field the samples experienced was about 2.56 T for over 100 cycles during which time the temperature was kept at about 4.5 K for approximately 300 days. Before and after the exposure, the susceptibility was measured by a superconducting quantum interference device and it was confirmed that the austenitic phase was stable and did not produce any additional martensite by the long term exposure to the high magnetic fields at cryogenic temperatures

[en] High resolution angle-resolved photoemission measurements have been carried out on (La_{1.4 -x}-Nd _0.6Sr_x)CuO₄ , a model system with static one-dimensional (1D) charge ordering (stripe), and (La_{1.8 5}-Sr _0.15)CuO ₄ , a high temperature superconductor (T_c=40 K) with possible dynamic stripes. In addition to the straight segments near (π,0 ) and (0,π ) antinodal regions, we have identified the existence of spectral weight along the [1,1] nodal direction in the electronic structure of both systems. This observation of nodal state, together with the straight segments near antinodal regions, reveals the dual nature of the electronic structure of stripes due to the competition of order and disorder

[en] The spatial field distribution in the flux line lattice state of La_2-xSr_xCuO₄ (LSCO) has been studied by muon spin rotation (μSR). In single-crystalline LSCO samples with x=0.13, 0.15, and 0.19, we have observed large vortex cores at low magnetic induction (≤0.5 T). The possibility of observing a field-induced antiferromagnetic component associated with such large vortex cores is discussed

[en] We have investigated control of microstructure, that is, the rearrangement of martensite variants (crystallographic domain), in a disordered Fe-31.2Pd (at.%) single crystal and an ordered Fe₃Pt single crystal, exhibiting cubic to tetragonal martensitic transformation at 230 and 85 K, respectively. When a magnetic field is applied along the [001] direction to the specimen with the multi-variant state, the specimen expands along the field direction for Fe-31.2Pd and contracts for Fe₃Pt, because the specific variant which reduces the magnetocrystalline anisotropy most will be selected to grow by consuming other variants. The fraction of such variants reaches 100% for Fe-31.2Pd but does not for Fe₃Pt. In the field removal process, part of the field-induced strain recovers for Fe₃Pt but not for Fe-31.2Pd. The recoverable strain of Fe₃Pt depends on temperature and shows a maximum value of nearly 1% at 20 K. From the magnetization curve, the energy dissipated due to the rearrangement of variants by a magnetic field is obtained to be about 260 kJ m^-3 for Fe-31.2Pd and about 180 kJ m^-3 for Fe₃Pt. This is of the same order of magnitude as that evaluated from the stress-strain curve of Fe-31.2Pd, meaning that the rearrangement of variants by a magnetic field occurs by nearly the same path or process as that by external stress. On the basis of these results and magnetocrystalline anisotropy constants of martensite phases, the mechanism of rearrangement of variants under a magnetic field is discussed

[en] High resolution angle-resolved photoemission measurements have been carried out on (La 1.4-x Nd 0.6 Sr x)CuO4, a model system with static stripes, and (La 1.85 Sr 0.15)CuO4, a high temperature superconductor (Tc=40K) with possible dynamic stripes. We have identified the existence of nodal spectral weight and its associated Fermi surface in the electronic structure of both the static and dynamic stripe systems. The ARPES spectra in the nodal regions show well-defined Fermi cut-off, indicating a metallic character of this charge-ordered state

[en] Effect of magnetic field on disorder-order transformation in CoPt has been investigated. Single crystals of disordered (A1-type) CoPt were heat-treated at 773 K for 0.5 h under various magnetic fields up to 10 T applied along the [001]_A1direction, and then annealed at 1023 K for 3 h under zero magnetic field. When the magnetic field in the first stage of ordering heat-treatment is larger than 0.5 T, a single variant state of L1₀-type ordered phase with the easy axis (c-axis) being parallel to the applied magnetic field direction is obtained