DEVELOPMENT OF METHOD FOR MAGNETIZATION MEASUREMENT IN PULSED HIGH MAGNETIC FIELD COMBINED WITH HIGH PRESSURE AND LOW TEMPERATURES

高压低温相结合的脉冲强磁场磁化测量方法的研制

基本信息

批准号：
12440102
负责人：
KINDO Koichi
金额：
$ 9.09万
依托单位：
OSAKA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2003
项目状态：
已结题

项目摘要

Former highest magnetic field by non-destructive magnet was 80.3 T with pulse duration of 8 msec. The recorded field has been renewed by multi-layer coil with inner reinforcement. New highest field is 80.8 T with the duration of 25 msec. Testing the life-time of the magnet makes it clear that the field of 67.5 T can be generated more that 40 shots.Outer diameter (D) of the ring for reinforcement of the magnet is minimized. D of 150 mm was used for the short pulse magnet with the duration of 7 msec. In the case of 70 mm, the magnet was destroyed at the field of 50 T but 90 mm-ring survived after highest field-shot. Through the test of the ring, D is decided to be 100 mm. The small ring has a great advantage that the magnet can be cooled down quickly, e.g., we can generate a 60 T shot every 15 minutes.Co-axial type of magnetization-pick-up-coil (MPC) has been installed in the dilution refrigerator. The problem that the inhomogeneous field has much influence on the signal for other type of MPC is solved by the co-axial MPC and the measurement accuracy is improved.Applying ZYLON^<TM> to the reinforcement of high-pressure cell has made it possible to carry out the high field magnetization measurement under high pressure. Usual high-pressure cell is made of Cu-Be and 1 GPa can be obtained easily but eddy current induced by pulsed field increases temperature. Thin pressure cell reinforced by ZYLON will provide precise measurement.The high field magnetization measurement at very low temperatures has shown a great progress. Field induced magnetic ordering was observed in the magnetization curves of the Haldane material NDMAZ. The magnetization measurement in the spin gap material SrCu_2(BO_3)_2 shown the magnetization 1/8-, 1/4-, 1/3-plateaux clearly.

以前无损磁体的最高磁场为 80.3 T，脉冲持续时间为 8 毫秒。记录的场已通过带有内部加固的多层线圈更新。新的最高场为 80.8 T，持续时间为 25 毫秒。测试磁铁的寿命表明，发射 40 次以上可产生 67.5 T 的磁场。用于加固磁铁的环的外径 (D) 已最小化。 150mm的D用于持续时间为7毫秒的短脉冲磁体。在 70 毫米的情况下，磁体在 50 T 的磁场中被破坏，但 90 毫米的环在最高磁场照射后幸存下来。通过对环的测试，确定D为100mm。小环有一个很大的优点，就是磁体可以快速冷却，例如每15分钟我们可以产生60T的弹丸。稀释器中安装了同轴型磁化拾取线圈（MPC）冰箱。同轴MPC解决了其他类型MPC存在的不均匀场对信号影响较大的问题，提高了测量精度。将ZYLON^<TM>应用于高压室的加固，使之成为可能。进行高压下的强磁场磁化强度测量。通常的高压室由Cu-Be制成，很容易获得1 GPa，但脉冲场感应的涡流会增加温度。 ZYLON 增强的薄型压力传感器将提供精确的测量。极低温度下的高场磁化测量已显示出巨大的进步。在 Haldane 材料 NDMAZ 的磁化曲线中观察到场感应磁序。自旋间隙材料SrCu_2(BO_3)_2的磁化强度测量清楚地显示出磁化强度1/8-、1/4-、1/3-平台。