HgBCO和PrBCO的正常态的1/f噪声研究

在１００ ～３００Ｋ温度范围内测量了Ｈｇ１２１２ 相块材和薄膜样品的正常态的１／ｆ 噪声,结果显示高质量薄膜的噪声水平为１０４ 量级,已和ＹＢＣＯ 外延膜及单晶相近．还测量了ＰｒＢａ２Ｃｕ３Ｏ７ － δ（ＰｒＢＣＯ） 微桥样品１／ｆ 噪声的尺寸依赖性,发现在ａｂ 面上,存在着与涨落相关的特征尺度,约为１０２μｍ 的量级．样品宽度降到该尺寸以下时,噪声水平急剧下降．在两个体系中,实验结果均和ＤｕｔｔａＨｏｒｎ 热激活模型进行了比较．     

HgBa2CuO2正常态1/f噪声行为的研究

我们在１００－３００Ｋ温度范围测量了ＨａＢａ２ＣｕＯ２（Ｈｇ－１２１２）相块材样品和不同质量的Ｈｇ－１２１２相薄膜样品,发现Ｈｇ－１２１２相膜的噪声温行为显示较强的样品个性。     

A STUDY ON THE ULTRASONIC VELOCITY AND ATTENU-ATION IN NdFeB MAGNET WITHIN THE TEMPERATURE RANGE OF 80-300K(Ⅰ)

The ultrasonic velocity V and attenuation A of both longitudinal and shear waves in an anisotropic NdFeB magnet were measured over the temperature range from 80K to 300 K by the pulse echo method. The anisotropy of the ultrasonic wave propagating in a NdFeB magnet was observed. Anomalous changes in both V-T and A-T curves in the temperature range of 110-160 K were found, which might be due to the spin reorientation phase transition of Nd2Fe14B.     

铜铌稀合金超薄膜的弱局域电性

在 4.2到 2 5K范围内测量了 2 0纳米稀掺杂铜铌超薄膜 (Cu99Nb1 ,Cu95 Nb5 )的电阻及磁导随温度的变化 ,没有观察到超导的迹象 ,而且样品的磁导都表现出典型的弱局域性质 .通过与理论的拟合 ,得到描述弹性散射 ,非弹性散射 ,自旋 轨道散射和磁散射的特征磁场和特征迟豫时间 .Cu95 Nb5 的各种特征迟豫时间均比Cu99Nb1 的小 .铌的加入不仅很大地影响了杂质引起的电子 电子散射 ,同时也是导致样品的弹性散射时间与自旋 轨道散射时间之比τ0 /τso偏离Abrikosov Gorkov关系的主要原因     

磁场下对近藤绝缘体CeNiSn的研究

测量了ＣｅＮｉＳｎ的一系列磁物性，发现在４．５Ｋ下，ＣｅＮｉＳｎ的磁化曲线在３Ｔｅｓｌａ处有拐点，并且发现４Ｔｅｓｌａ磁场可以压抑４００Ｇａｓｓ磁场下测量的磁化率随温度变化曲线在１０Ｋ附近的峰，但磁阻测量表明４Ｔｅｓｌａ磁场并没有改变ＣｅＮｉＳｎ的近藤绝缘体性质．说明磁化率曲线在１０Ｋ附近的峰的形成与近藤绝缘体的形成无本质联系，磁场对能隙的影响中，Ｚｅ－ｍａｎ劈裂的作用并不强，而主要是通过破坏形成准粒子的局域ｆ电子与ｃ电子相互作用而达到压抑能隙的．     

A STUDY ON THE ULTRASONIC VELOCITY AND ATTENU-ATION IN NdFeB MAGNET WITHIN THE TEMPERATURE RANGE OF 80 - 300K (Ⅱ)

Based on the ultrasonic measurements of an isotropic NdFeB magnet in the temperature range of 77 - 300 K, it was found that the elastic parameters, such as Young's modulus E, and Poisson ratio v, change abruptly near the spin reorientation temperature Tsr. This indicates that soft mode emerges in the process of spin reorientation. Thermal hysteresis was observed during heating-up and cooling-down processes. Both Debye temperature and heat capacity were calculated, which suggests that the magnetic entropy of the Nd-sublattice is larger in easy-cone state than in easy-axis state.