Development of High-Pressure Precise Magnetization Measurement System and Studies of Magnetic Phase Transitions under High Pressure

高压精密磁化测量系统研制及高压磁相变研究

• 批准号: 09640434
• 负责人: ISHIZUKA Mamoru
• 金额: $ 1.98万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640434/
• 关键词: high pressure; SQUIDmagnetometer; magnetization measurement; diamond-anvil cell; vanadium; superconducting transition temperature; 磁気測定

We have improved the performance of the high-pressure magnetization measurement system consisting of a diamond-anvil cell (DAC) and a SQUID vibrating coil magnetometer in order to increase the pressure range of a high-pressure research in magnetism and superconductivity to more than 100 GPa. Results are as follows. (1) The sensitivity of the system has been increased by a factor of 10 by compensating the magnetic-field signal which previously prevented us from applying larger magnetic field than 3 Oe. (2) Thermal insulation of the actuators for vibration of the SQUID detection coil from the DAC has been improved, resulting in an increase in the temperature of the measurements by a factor of more than two. (3) Using this system we have investigated a pressure-induced magnetic phase transition in CrTe (T_c=330-350 K) and pressure effect on superconducting transition of vanadium at megabar. A magnetic phase transition in CrTe at around 3.5 GPa was first reported by Grazhdankina et al., but their results are controversial because the sample they used was not single phase and the experimental accuracy seems not to be enough for establishing the magnetic state. We have observed a disappearance of the ferromagnetism of CrTe at 6-7 GPa for samples with good quality. The superconducting transition temperature T_c of vanadium increases linearly with pressure up to 50 GPa. Pressure dependence of T_c has been measured up to 112 GPa so as to investigate to what extent such a monotonic increase in T_c would hold. T_c at 112 GPa was found to be more than three times as large as that at ambient pressure and to still increase with pressure. This value of T_c is the largest one observed in single elements.

我们改进了由金刚石砧室（DAC）和SQUID振动线圈磁力计组成的高压磁化测量系统的性能，以便将磁学和超导高压研究的压力范围提高到100 GPa以上。结果如下。 (1) 通过补偿磁场信号，系统的灵敏度提高了 10 倍，而之前我们无法施加大于 3 Oe 的磁场。 (2) DAC 的 SQUID 检测线圈振动执行器的隔热性能得到改善，导致测量温度升高两倍以上。 (3) 利用该系统，我们研究了 CrTe (T_c=330-350 K) 中压力诱导的磁相变以及兆巴下钒超导转变的压力效应。 Grazhdankina等人首先报道了CrTe在3.5 GPa左右的磁相变，但他们的结果存在争议，因为他们使用的样品不是单相，并且实验精度似乎不足以建立磁态。对于质量好的样品，我们观察到 CrTe 的铁磁性在 6-7 GPa 下消失。钒的超导转变温度T_c随着压力线性增加直至50 GPa。 T_c 的压力依赖性已测量到高达 112 GPa，以便研究 T_c 的单调增加在多大程度上成立。发现 112 GPa 下的 T_c 是环境压力下的三倍以上，并且仍随压力而增加。 T_c 的该值是单个元素中观察到的最大值。

项目成果

石塚 守: "超高圧下精密磁化測定装置の最近の進展" 大阪大学極限科学研究センター報告書. 2. 48-51 (1997)

Mamoru Ishizuka：“超高压下精密磁化测量设备的最新进展”大阪大学极限科学研究中心报告2. 48-51 (1997)。

Mamoru Ishizuka: "Pressure-induced structural phase transition in the two-dimensional Heisenberg ferromagnet K_2CuF_4" Physical Review B. Vol57,No1. 64-67 (1998)

Mamoru Ishizuka：“二维海森堡铁磁体 K_2CuF_4 中的压力诱导结构相变”物理评论 B. Vol57，No1。

Mamoru Ishizuka: "Pressure-Induced Structural Phase Transition in the Two-Dimensional Heisenberg Ferromagnet KzCuF_4" Phys.Rev.B. 57. 64-67 (1998)

Mamoru Ishizuka：“二维海森堡铁磁体 KzCuF_4 中的压力诱导结构相变”Phys.Rev.B。

Mamoru ISHIZUKA: ""Measurements of Supercondcting Transitions at Pressures up to 83 GPa"" to be published in Physica B. (1999)

Mamoru ISHIZUKA：““压力高达 83 GPa 时超导转变的测量””将在 Physica B 上发表（1999 年）

Mamoru Ishizuka: "Measurements of Superconducting Transitions at Pressures" Physica B. (1999)

Mamoru Ishizuka：“压力下超导转变的测量”Physica B. (1999)