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Article: Current Status of the Tsukuba Magnet Laboratory
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ABSTRACT: The Hybrid Magnet Apparatus has been fundamentally reconstructed in order to boost the performance of the Tsukuba Magnet Laboratory and yield high quality research results in a wide variety of research areas. The stability of the magnetic field, or more precisely, the stability of the current has been much improved. Ahigh stability field has been attained in the Hybrid Magnet, providing an opportunity for NMR measurements at 35T. In order to provide more flexible operation of the water cooled magnet (WM) and to decrease the energy requirements of the facility, the water cooling system was modified to utilize indirect cooling via a heat exchanger, and the circulating water flow was increased eightfold. In the newly adopted procedure, the water exiting the chiller is led directly to the heat exchanger resulting in high cooling efficiency. By repairing the water system, the water temperature can be controlled regardless of any field changes. Thus, the number of variations in possible experiments has been greatly increased. The helium-cooling system for the superconducting magnet was replaced with a smaller one. In addition, the laboratory is participating in the CO2 emissions trading program of the Japanese Ministry of the Environment, and is being managed to meet CO2 emissions reduction targets. KeywordsHybrid magnet-NMRJournal of Low Temperature Physics 04/2012; 159(1):358-365. · 1.19 Impact Factor -
Article: Evidence for spin-glass state in nonmagnetic atom disorder compound Pr2AgIn3
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ABSTRACT: A systematic investigation of magnetic properties has been performed on intermetallic compound Pr2AgIn3, which crystallizes in a disordered hexagonal CaIn2-type structure. We present the experimental results of ac and dc susceptibility, magnetization, magnetic relaxation, specific heat and electrical resistivity measurements. The results provide clear evidence for the formation of spin-glass state in Pr2AgIn3 below a spin freezing temperature Tf~3.7 K accompanied with a short-range magnetic order. The spin-glass behavior of Pr2AgIn2 is discussed and compared with that observed for the isostructural compounds Ce2AgIn3 and Nd2AgIn3 as well as other 2:1:3 spin-glass materials. The spin-glass state in Pr2AgIn3 can be considered to originate from the continued site randomness of the nonmagnetic elements, Ag and In, which introduce the random distribution of the RKKY interactions.Journal of Physics Conference Series 09/2011; 320(1):012041. -
Article: Magnetic anisotropy and spin-glass behavior in single crystalline U2PdSi3.
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ABSTRACT: We present the magnetic and transport properties of single crystalline U(2)PdSi(3) measured with the magnetic field (H) (or measuring current, I) applied along two typical crystallographic directions, i.e. H ⊥ c-axis and H c-axis (or I ⊥ c-axis and I c-axis). For both directions, a spin-glass state is confirmed to form at low temperature with the same spin freezing temperature T(f) (=11.5 K), initial frequency shift δT(f) (=0.023) and activation energy E(a)/k(B) (=90.15 K) in zero dc field. Strong anisotropy in magnetic and transport behavior is found to be a significant feature of U(2)PdSi(3). The unusual ferromagnetic-like anomaly in ac susceptibility and dc magnetization curves around T(m)=71 K is observed in the case of H c-axis but not in the cases of H ⊥ c-axis. The characteristic temperature T(ir), below which evident irreversible magnetism originated from random spin freezing can be observed, shows much stronger field dependence for H ⊥ c-axis than for H c-axis. Moreover, an unusual finding is that the electrical resistivity measurements indicate the formation of magnetic Brillouin-zone boundary gaps and much larger magnetic scattering for I ⊥ c-axis, while the coherent-Kondo-effect-like behavior is obvious for I c-axis. We also emphasize that no resistivity minimum can be detected down to 2.5 K for either direction. The observed magnetic and transport behaviors are compared with those in polycrystalline U(2)PdSi(3) and other 2:1:3 intermetallic compounds.Journal of Physics Condensed Matter 02/2011; 23(7):076003. · 2.55 Impact Factor -
Article: Magnetization studies of RHQT-processed Nb3Al wires for high-field accelerator magnet applications
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ABSTRACT: Rapid heating/quenching and transformation (RHQT)-processed Nb3Al wires possess better strain tolerance than Nb3Sn wires and exhibit similar high-field properties. Therefore, Nb3Al wires might be promising candidates for use in future high-field accelerator magnets. For this reason, we have been developing RHQT-processed Nb3Al wires for a number of years. During this development, magnetization measurements on several samples have been carried out as a function of either temperature or the magnetic field. This paper presents some of the results of the magnetization measurements performed.Journal of Physics Conference Series 07/2010; 234(2):022040. -
Article: Study of Wires for High-Field Accelerator Magnet Applications
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ABSTRACT: Rapid heating, quenching and transformation (RHQT)-processed Nb<sub>3</sub>Al wires possess better strain tolerance than Nb<sub>3</sub>Sn wires. However, RHQT-processed Nb<sub>3</sub>Al wires so far developed show lower non-copper critical current density (J<sub>c</sub>) than recently developed high-J<sub>c</sub> Nb<sub>3</sub>Sn wires in the field range of 12-15 T. Therefore, the development of Nb<sub>3</sub>Al wires having enhancing J<sub>c</sub> in this field range is a major concern for accelerator magnet designers. Among a number of fabrication parameters that might affect J<sub>c</sub> properties, we analysed the effect of thickness of Al and Nb foils in the jelly-roll-shaped filaments embedded in the precursor wires. Mechanical and superconducting properties of these wires with various Al-foil thicknesses in the filaments were investigated.IEEE Transactions on Appiled Superconductivity 07/2010; · 1.04 Impact Factor
