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The magnetization reversal process has been studied in a series of four TbFeCo films over the temperature range 300-460 K. The films were characterized by time decay, dynamic coercivity, Kerr imaging, and torque measurements. For a film with a sputter-etched SiN underlayer, the reversal process at low temperatures was dominated by nucleation followed by rapid domain wall motion. The low temperature relaxation curves for this sample were analyzed using a Fatuzzo model. At high temperatures, the Fatuzzo model did not apply. For the other films, with no etching, relaxation curves were logarithmic at all temperatures. All activation volumes increased with increasing temperature and decreased with increasing sputtering pressure. The magnetic anisotropy direction changed from perpendicular to in-plane as the argon sputtering pressure was increased. [ABSTRACT FROM AUTHOR]

Examines the relationships between the magnetic properties and the film structure of manganese/aluminum multilayers. X-ray diffractions; Comparison between saturation magnetization and magnetic anisotropy; Difference of the magnetic anisotropy in the hysteresis curves.

Presents a study which reported the measurement of fundamental magnetic properties and the resulting magnetization structure of single-crystal films. Anisotropy of the films; Hysteresis loops of the thin-film sample; Ferromagnetic resonance of the films.

We have been developing Nb3Al high-field accelerator magnets with the aim of upgrading the luminosity of the Large Hadron Collider. In this program, four kinds of Ta-matrix Nb3Al strands with slightly different cross-sectional structures (K1, K2, K3 and K4 strands) were designed and fabricated. The non-copper Jc values of these strands were 700–800 A/mm^2 at 15 T and 4.2 K. The cabling work of these strands was performed at Fermilab, and the superconducting properties of the cables were studied using the extracted strands from the cables. In this paper, we report on the fabrication experience for the strands and cables. The results obtained from this study are also presented. [ABSTRACT FROM PUBLISHER]

Research and development of Nb3Al strands and cables for a high field accelerator magnet is ongoing under the framework of the CERN-KEK collaboration. In this program, new Ta-matrix Nb3Al strands were developed and their mechanical properties and superconducting properties were studied. The non-Cu Jc values of these strands were 750\sim 800\ \A/mm^2 at 15 T and 4.2 K. Using these strands, test fabrication of 27-strand Rutherford cable was carried out in collaboration with NIMS and Fermilab. The properties of the strands extracted from the cable were examined and it was found that there was no degradation of the superconducting properties of the strands. In this paper, we report the fabrication of the strands and the cable in brief and present some of the results obtained by studying their properties. [ABSTRACT FROM AUTHOR]

Characteristics of recently developed Nb3Al strand though the RHQT (rapid heating/quenching and transformation) process are described. One kilometer-long copper stabilized Nb3 Al round strands were economically fabricated with ion-plating and electroplating. The copper electroplating was successfully done with the high velocity of 5 m/h. A strong bonding between the copper and the precursor was achieved, and the mechanical rolling test did not show the separation of the copper stabilizer from the precursor. The rolled Nb3 Al strands showed no degradation both in critical current density and RRR value. Magnetic instability at 4.2 K at low fields was apparently improved on the recent F3 strand, relative to the previously F1 stand because a tantalum was used for the interfilament matrix of precursor. The large magnetic flux jumps, which were observed with the F! strand, were suppressed at 4.2 K, although appeared again below 3.0 K. The twisted strands are shown to be effective to reduce the time-dependent eddy current coupling. It was obtained 48 μm of Deff on F3 strand with twist pitch of 45 mm. In addition, the transverse pressure test for the F1 Nb3 Al strand was performed at 4.2 K and 12 T. The critical, current did not degrade with the transverse pressure up to 210 MPa. [ABSTRACT FROM AUTHOR]

Long Nb3Al strands with copper stabilizer are promising for future high field accelerator magnets. A 1.2 kilometer Nb3A1 strand with Cu stabilizer was fabricated at the National Institute for Materials Science in Japan. Using this strand a 30 meter Cu stabilized Nb3Al Rutherford cable was made for the first time by a collaboration of NIMS and Fermilab. The Nb3Al strands extracted from cable with a relatively low packing factor showed almost no Jc degradation. But the extracted strands from the highly compacted cable showed some degradation in both Jc and n value, which may be caused by local separation of the copper stabilizer. Still, its Jc degradation is lower than that of typical Nb3Sn strands. The current limit due to magnetic instability in low field is about 500 A at 4.2 K. The magnetization of the strands, which was measured with balanced coils at 4.2 K, showed large flux jumps, usually around 1.5 T. This value is much larger than the Bc2 (4.2 K) of the Nb matrix, which is around 0.4 Tesla. The magnetic instability of the Nb3Al strand at low field is not completely understood, but it might be explained by the superconducting coupling current through the Nb matrix. [ABSTRACT FROM AUTHOR]

The replacement of Nb matrix with Ta for rapid-heating, quenching and transformation annealing (RHQT) processed Nb3Al conductor seems to be advantageous for facilitating the RHQ operation due to a higher mechanical strength at elevated temperatures and less reactivity with the molten Ga in the quench bath and suppressing flux jumps in low magnetic fields. We have fabricated three grades of the Ta matrix precursor, in which the volume fraction of Ta matrix is different, so as to examine the drawability of such Ta matrix precursors. Also examined are the effects of using the Ta matrix on the RHQ condition, Tc values after quenching and subsequent annealing, respectively, Jc (core), overall residual resistivity, and magnetization curves. We have succeeded in drawing all of Ta matrix precursors and confirmed the favorable existence of a plateau region in the IRHQ - Tc relationship even for the Ta matrix RHQT Nb3Al conductors. The resulting superconducting properties were comparative to those of Nb matrix conductors. The replacement of Nb matrix with Ta was very effective in suppressing flux jumps even at 4.2 K. [ABSTRACT FROM AUTHOR]

We have measured the strain, magnetization, and specific heat of the antiferromagnetic (AFM) Kondo semiconductors Ce T2 Al10 (T = Ru and Os) under uniaxial pressures applied along the orthorhombic axes. We found a linear dependence of TN on the b -axis parameter for both compounds under uniaxial pressure P || b and hydrostatic pressure. This relation indicates that the distance between the Ce- T layers along the b axis is the key structural parameter determining TN. Furthermore, the pressure dependence of the spin-flop transition field indicates that Ce-Ce interchain interactions stabilize the AFM state with the ordered moments pointing to the c axis. [ABSTRACT FROM AUTHOR]

EuCo 2 Ge 2 with the tetragonal structure is a Eu-divalent antiferromagnet with the Néel temperature T N = 23 K. The magnetic easy-axis corresponds to the [100] direction ( a -axis), while the [001] direction ( c -axis) is a hard-axis. The magnetization for H ∥ [ 100 ] indicates a metamagnetic transition at 25 kOe and saturates above 75 kOe. On the other hand, the hard-axis magnetization increases approximately linearly and saturates above 110 kOe. The magnetic phase diagram was constructed. A characteristic feature in EuCo 2 Ge 2 is known as a valence transition under pressure, from Eu 2 + δ to Eu 3 − δ ′ ( δ , δ ′ < 1 ). We also clarified the valence transition by measuring the electrical resistivity under pressure. The valence transition occurs at 3 GPa, with a hysteresis, and terminates at about 4.5 GPa. Further increasing pressure, the electronic state is changed into a moderate heavy fermion state and approaches the nearly trivalent electronic state. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the magnetic and electronic properties of an antiferromagnet and pressure-induced superconductor CePd5Al2 by measuring the magnetization and de Haas–van Alphen effect, together with the electrical resistivity under pressure and magnetic field. Magnetic measurements including the high field magnetization at 1.3K reveal several magnetic transitions and quite complex magnetic phase diagram of this compound. Electrical resistivity measurements have been performed using diamond anvil cell up to 12GPa for the magnetic fields and [100]. The upper critical field in superconductivity is anisotropic between and [100] in the tetragonal structure, reflecting the quasi-two dimensional electronic state. [Copyright &y& Elsevier]

Abstract: High-field magnetization measurements of ( and Ge) and were carried out up to 50T. The magnetization of at 1.3K increases linearly, with a small metamagnetic transition at 7.8 and 10.5T for H//[110] and [100], respectively, and saturates at 27T for H//[100] and [110], while the magnetization also saturates at 15.5T for H//[001], without the metamagnetic transition. The high-field magnetization of at 1.3K shows no metamagnetic transition. [Copyright &y& Elsevier]

Abstract: We succeeded in growing single crystals of (R: rare earth) and measured the magnetic susceptibility and magnetization. The lattice constants of with the tetragonal structure are well understood from a viewpoint of the lanthanide contraction, except with the divalent Yb ion. Most of compounds order antiferromagnetically. indicates two metamagnetic transitions at and below for the magnetic field along the [001] direction. The saturation moment of is in good agreement with a staggered Nd moment determined by the neutron scattering experiment. The similar metamagnetic transitions were observed in , and . [Copyright &y& Elsevier]

Abstract: The magnetization of single crystalline has been investigated in the antiferromagnetically ordered state up to 54T. At 4.2K, for , the magnetization shows field-induced multi-step jumps and several plateau regions above 16T, and finally reaches saturation at about 28T. The magnetization in the (001) plane, on the other hand, shows only one large jump at and 12T for and , respectively, and gradually increases toward saturation above . The magnetization curves have also been measured at higher temperatures to establish the magnetic phase diagram. [Copyright &y& Elsevier]