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The Tsukuba Magnet Laboratory (TML) of the National Institute for Materials Science has been producing epoch-making achievements in the history of high-field magnets. TML is also known as one of the largest high magnetic field facilities in the world and opened to domestic and international users. As a milestone in the 1-GHz NMR project, a 920-MHz high-resolution NMR magnet using Nb 3 Sn innermost coil was developed in order to accelerate studies to obtain stereoscopic protein structures. Measurements for analyzing the stereoscopic structure of protein molecules using 920 MHz NMR magnet have been performed since July 2002.

A resistive insert magnet consisting of Bitter-type coils was fabricated, incorporated into the 400-mm bore of the superconducting outsert, and tested under a backup field of 14.2 T. This hybrid magnet generated a total field of 37.3 T in the center of a 32-mm room-temperature bore. At this magnetic field, the operating current of the resistive insert magnet was 33.25 kA at a voltage of 431 V. This insert magnet is divided into three coaxial coils. The bitter plates of the two inner coils are made of hard-worked Cu–Ag plates, and those of the outermost coil are made of GlidCop AL-25. The thickness of the plates used in the two inner coils was 0.84 mm, and the 0.2% proof stress in the direction parallel to the roll work was about 800 MPa at 375 K. This temperature is designed to be the maximum of the innermost coil at 37.3 T. Elongated cooling channels were punched in a staggered formation in these plates. The flow rate of the cooling water was 0.141 m 3 /s at the maximum field. Regular operation up to 35 T started from June 2000 at the Tsukuba Magnet Laboratory.

The Tsukuba Magnet Laboratory (TML) of the National Research Institute for Metals has been producing epoch-making achievements in the history of high-field magnets. Its hybrid magnet is in operation, providing users with fields up to 30 T in a 52-mm∅ room-temperature bore. In September 1999, the hybrid magnet generated a field of 37.3 T in a 32-mm∅ room-temperature bore, which was the world record of the steady-state fields at that time. The superconducting magnet system operating at TML succeeded in generating 23.4 T using two Bi-2212 insert coils. As a milestone in the 1 GHz NMR magnet project carried at TML, a 900 MHz NMR magnet was successfully manufactured and operated in a persistent mode. A challenging program in which different types of superconducting magnets are developed to meet specific requirements is in operation. One example is a magnet designed to generate uniform magnetic force fields defined as B grad B in a sample space. TML is now a user facility open to domestic and international users. Efforts will be continued to improve its high-field facilities by developing magnet technology as well as materials for high-field magnets.

We have developed a 920 MHz NMR system and performed the proton NMR measurement of ethylbenzene and water using the superconducting magnet operating at 21.6 T ( 920 MHz for proton), which is the highest field produced by a superconducting NMR magnet in the persistent mode. From the NMR measurements, it is verified that both homogeneity and stability of the magnet have a specification sufficient for a high-resolution NMR. The sensitivity has been examined by 1 H NMR of 0.1% ethylbenzene in Wilmad 555 tube and obtained the signal-to-noise ratio as S/N=2981, which is the highest record, to our knowledge, among the room temperature measurements.

Cu-NMR results on field-induced magnetic long-range (LR) order in structural disordered single crystal Sr14Cu24O41 (Sr14) are presented. Drastic broadening of both the ladder/Zhang Rice-NMR spectra in H∼11 T occurs below T N ∼20 K . Meanwhile, another evidence of LR ordering is revealed in nuclear relaxation measurement. Staggered polarization originates from single-hole localization on the ladders. The growing interlayer coupling under H, as a result, leads to the appearance of the LR order as well as in the other spin-ladder compounds.

In the overdoped region of x=0.20−0.24 in La2−xSrxCuO4, the rapid decrease in 1 T 1 and the Knight shift just below Tc have been observed as well as in the lightly doped region of x⩽0.15, verifying the presence of superconducting phases even in the overdoped region from a microscopic level. At low T, a gapless feature of superconductivity has been found from the characteristic behavior of a T1T=constant law and the presence of the residual spin Knight shift. This behavior of T1 and the Knight shift are explained in terms of a d-wave model in which a finite residual density of states is taken into account at the Fermi level associated with a pair-breaking effect.

High-pressure NMR measurements on a single crystal of hole-doped two-leg ladder compound, Sr 2 Ca 12 Cu 24 O 41 , have been carried out up to ∼1.7 GPa. The activated T -dependences of T 1 and Knight shift at 1.7 GPa assured the persistence of the spin gap in this system.