Magnetic Ordering and Nonlinear Response of Complex Systems Related to C_<60>

C_<60>相关复杂系统的磁序和非线性响应

• 批准号: 07640513
• 负责人: HAGIWARA Makoto
• 金额: $ 1.41万
• 依托单位: Kyoto Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640513/
• 关键词: cluster; complex system; magnetism; interaction; nonlinear susceptibility; graphite intercalation compound; ceramic superconductor; oxide glass; 逐次相転移; セラミック超伝導体; 有機超伝導体; cluster; complex system; magnetism; interaction; nonlinear susceptibility; graphite intercalation compound; ceramic superconductor; oxide glass; 逐次相転移; セラミック超伝導体; 有機超伝導体

Several kinds of complex magnets and superconductors containing crystallographic clusters have been studied chiefly by nonlinear magnetic susceptibility (x_2) measurement. Effects of characteristic interaction at the heterogeneous boundaries have been discussed for the complex systems.First of all, a measurement system with a new cryostat apparatus was designed and constructed in order to observe nonlinear susceptibility under severe experimental conditions with both 1ow frequency and weak field amplitude. Using the system, we have been able to examine higher harmonics (up to 9'th order) as well as fundamental of the magnetic responses for each complex materia1.For CoCl_2-GIC,every harmonic component of the AC magnetization shows positive peak anomaly near the upper critical temperature, when the excitation amplitude (h) is larger than 0.6Oe. This fact confirms that x_2 shows negative divergence at the critica1 temperature. It is a1so proved to be an intrinsic phenomenon that the profile of the x_2 anomaly changes into anti-symmetric one when h becomes smaller than 0.3Oe.For ceramic superconductor YBa_2Cu_4O_8, x_2 shows sharp peak anomaly at a certain critical temperature enough below T_c of the crystalline specimens. This anomaly is speculated to be a reflection of frustrated phase ordering transition of the d-wave superconducting grains in the ceramics.For glassy magnet CaO-SiO_2-0.5Fe_2O_3, magnetic interaction between deposited ferrimagnetic clusters and amorphous boundary region around them is suggested. The interaction causes drastic descending shift of the ESR field as well as Curie-Weiss law of the DC susceptibility.In addition, despite several attempts to synthesize IBr-C_<60>, no spontaneous magnetization has been found in any compounds obtained by using various partial pressure of IBr for the doping.

主要通过非线性磁敏感性（X_2）测量研究了几种含有晶体簇的复杂磁体和超导体。对复杂系统的异质边界上的特征相互作用的影响。首先，设计和构造了具有新的低温恒温器设备的测量系统，以观察到具有1of频率和弱场幅度的严重实验条件下的非线性敏感性。使用该系统，我们已经能够检查更高的谐波（最多9'ter阶），以及每个复杂材料的磁反应的基础。对于COCL_2-GIC，当激发幅度幅度（H）大于0.6OE时，AC磁化的每个谐波分量都显示在上部临界温度附近的正峰值异常。这一事实证实X_2在批评性温度下显示出负分歧。事实证明，当h时h时X_2异常的轮廓变为抗对称性时，当H变小小于0.3OE时，X_2异常的轮廓会变成反对称的现象。对于陶瓷超导体YBA_2CU_4O_8，X_2在某种临界温度下显示出尖锐的峰值峰值异常，在某些临界温度下方，足以在某些临界温度下方的T_C下方t_c t_c的T_C t_c的Crystalline Specimens t_c。据推测，这种异常被认为是陶瓷中D波超导晶粒的沮丧相排序过渡的反映。对于玻璃磁铁CAO-SIO_2-0.5FE_2O_3，建议在它们周围沉积的铁磁簇和无偶治边界之间的磁相互作用。这种相互作用导致ESR场的急剧下降以及DC敏感性的Curie-Weiss定律。此外，尽管有几次尝试合成IBR-C_ <60>的尝试，但在使用IBR的各种ibr的浓度的各种压力的兴奋剂中都没有发现任何自发磁化。