Measurement of the upper critical field of optimally-doped YBa2Cu3O7-δ in megagauss magnetic fields
Measurement of the upper critical field of optimally-doped YBa2Cu3O7-δ in megagauss magnetic fields
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DOI：
10.1088/1367-2630/9/3/047
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发表时间：
2007-03-02
影响因子：
3.3
通讯作者：
Miura, Noboru
中科院分区：
文献类型：
--
作者：
Sekitani, Tsuyoshi;Matsuda, Yasuhiro H.;Miura, Noboru
在平行于CuO_2面（B垂直于c）施加的高达600 T的强磁场（B）中，我们观察到了最佳掺杂YBa_2Cu_3 O_（7-δ）（T-c近似于90 K）从超导态到正常态的过渡。这是第一个系统的临界场测量在低温下的几何形状的B平行于CuO 2-平面使用超导体的Tc大于90 K。为了在短脉冲强磁场中进行高灵敏度的磁导率测量，我们开发了一种非接触式射频传输技术。通过使用电磁通量压缩产生高于200 T的超高磁场，而单匝线圈系统用于产生高达200 T的磁场。我们在250 T和5 K的温度下清楚地观察到超导态向正常态的电导率的交叉，以及临界场随温度的升高而系统地减小。在5 ~ 300 K的宽温度范围内绘制了场-温度相图。
We have observed crossover from superconducting state to normal state in optimally doped YBa2Cu3O7-delta (T-c similar to 90 K) in very high magnetic fields (B) up to 600 T applied parallel to CuO2 planes (B perpendicular to c). This is the first systematic critical field measurement at low temperatures in the geometry of the B parallel to CuO2-planes using superconductors with T-c greater than 90 K. In order to perform high-sensitivity magneto-conductivity measurements in short-pulsed high magnetic fields, we developed a contactless radio frequency transmission technique. Ultrahigh magnetic fields higher than 200 T are generated by using electromagnetic flux compression, while a single-turn coil system is used for generating magnetic fields up to 200 T. We observed clearly the crossover from the superconducting to normal state conductivity at 250 T at a temperature of 5 K, and a systematic decrease of the critical field with increasing temperature. The field-temperature phase diagram was constructed over a wide temperature range between 5 K and 300 K.