有机超导体的临界温度已达117K

高温超导体的转变温度Ｔｃ 正沿着三条路线被提高 .其一是铜氧化合物超导体 ,从 1986年发现镧系的ＬＳＣＯ和钇系的ＹＢＣＯ ,至 1993年Ｔｌ 2 2 0 1超导体的Ｔｃ 已达到 133Ｋ ,而在加压的条件下 ,Ｈｇ系的Ｔｃ 可达 16 4Ｋ .其二是轻主族元素化合物 ,以 2 0 0 1年发现的Ｔｃ～ 4 0Ｋ的ＭｇＢ2 为代表 .其三是有机超导体 ,1979年发现的第一个电荷转移盐有机超导体 ,其Ｔｃ 在 1Ｋ以下 ,后来这类材料的Ｔｃ 提高到约10Ｋ[1,2 ] .1991年在碱金属Ａ掺杂的Ａ3 Ｃ60 大块超导体中 ,观察到的Ｔｃ 为 18Ｋ .近年来 ,美国贝尔实验室等一些研究机构 …     

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1Ｐｈｙｓｉｃｓｉｎｔｈｅｗｈｉｒｌｗｉｎｄｏｆｏｐｔｉｃａｌｃｏｍｍｕｎｉｃａ ｔｉｏｎｓ (ＧｏｒｄｏｎＡ .Ｔｈｏｍａｓ ,ＤａｖｉｄＡ .Ａｃｋｅｒｍａｎ ,ＰａｕｌＲ .Ｐｒｕｃｎａｌｅｔａｌ .Ｐｈｙｓ .Ｔｏｄａｙ ,2 0 0 0 ,Ｎｏ .9)2ＤＮＡ ｉｎｓｐｉｒｅｄｅｌｅｃｔｒｏｓｔａｔｉｃｓ (ＷｉｌｌｉａｍＭ .Ｇｅｌｂａｒｔ ,ＲｏｂｉｊｎＦ .Ｂｒｕｉｎｓｍａ ,ＰｈｉｌｉｐＡ .Ｐｉｎｃｕｓｅｔａｌ .Ｐｈｙｓ .Ｔｏｄａｙ ,2 0 0 0 ,Ｎｏ .9)3Ｈｏｔ ｐｒｏｓｐｅｃｔｓｆｏｒｕｌｔｒａｃｏｌｄｍｏｌｅｃｕｌｅｓ (Ｂ…     

硼在高压下的超导电性

20 0 1年 1月ＭｇＢ2 超导电性 (Ｔｃ～ 39Ｋ)的发现 ,重新燃起了人们研究轻元素超导电性的兴趣 .表 1给出了迄今已发现的轻主族元素超导体和它们的Ｔｃ.其中碳超导电性 (Ｔｃ ～ 5 2Ｋ)是通过场效应电荷转移技术对Ｃ60 晶体进行空穴掺杂而实现的 ;大块铍的Ｔｃ 原本仅 2 6ｍＫ ,但在亚稳态薄膜样品中 ,它增加到了 10 5Ｋ .硼在常压下是半导体 ,用 4 88ｎｍ的Ａｒ离子激光照射 ,它展现出强的光电导 ,具有 1 6ｅＶ的能隙 .最近 ,来自美国华盛顿Ｃａｒｎｅｇｉｅ研究所的Ｅｒｅｍｅｔｓ等发现 ,由 2 0面体团簇分子Ｂ12 键联而成的β型多晶…     

PROGRESS IN PHYSICS CONTENTS OF VOLUME 21

ＮＵＩＮＢＥＲ 1ＭＡＲＣＨ 2 0 0 1ＤｅｆｅｃｔｓａｎｄＩｍｐｕｒｉｔｉｅｓｉｎＧａＮ ＸｕＸｉａｏｌｉａｎｇ ,ＳｈｉＣｈａｏｓｈｕ ,Ｓ .Ｆｕｎｇ ,Ｃ .Ｄ .Ｂｅｌｉｎｇ(1)…Ｘ ＲａｙＴｈｒｅｅ ＤｉｍｅｎｓｉｏｎａｌＭｉｃｒｏ ＩｍａｇｉｎｇＵｓｉｎｇＳｙｎｃｈｒｏｔｒｏｎＲａｄｉａｔｉｏｎＺｈａｎｇＹｕｘｕａｎ ,ＺｈａｎｇＸｉｎｙｉ(12 )……………………………………………………………………………ＰｒｏｇｒｅｓｓｏｆＳｙｎｔｈｅｓｉｓｏｆＳｕｐｅｒｈｅａｖｙＮｕｃｌｅｉＺｈａｎｇＦｅｎｇｓｈｏｕ ,Ｍｉ…     

A Novel OADM Based on Fiber Gratings

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｏｐｔｉｃａｌａｄｄ/ｄｒｏｐｍｕｌｔｉｐｌｅｘｅｒ (ＯＡＤＭ)ｉｓｔｈｅｋｅｙｃｏｍｐｏｎｅｎｔｏｆｏｐｔｉｃａｌｔｒａｎｓｐｏｒｔｎｅｔｗｏｒｋｓ(ＯＴＮ) .ＭａｎｙＯＡＤＭａｒｃｈｉｔｅｃｔｕｒｅｓｈａｖｅｂｅｅｎｒｅｐｏｒｔｅｄ ,ｓｕｃｈａｓｔｈｏｓｅｂａｓｅｄｏｎｗａｖｅｌｅｎｇｔｈｍｕｌｔｉｐｌｅｘｅｒｓ,ａｒｒａｙｅｄｗａｖｅｇｕｉｄｇｒａｔｉｎｇｓ(ＡＷＧ ) ,ａｃｏｕｓｔｏ ｏｐｔｉｃｔｕｎａｂｌｅｆｉｌｔｅｒｓ (ＡＯＴＦ) ,ｆｉｂｅｒＢｒａｇｇ ｇｒａｔｉ…     

超导临界特性及演示

利用ＹＢａ２Ｃｕ３Ｏ７－ｘ超导体室温下是正常态，具有高电阻，而在临界温度之下，则为超导态的特性，我们设计了一个简单的实验，演示了超导的主要特性，并定量地测量了超导体的临界电流ＩＣ。     

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1　Ｎｏｎｃｑｕｉｌｉｂｒｉｕｍ ｐａｔｔｅｒｎｓｉｎｇｒａｎｕｌａｒｍｉｘｉｎｇａｎｄｓｅｇｒｅｇａｔｉｏｎ(ＴｒｏｙＳｈｉｎｂｒｏｔ ,ＦｅｒｎａｎｄｏＪ.Ｍｕｚｚｉｏ .Ｐｈｙｓ .Ｔｏｄａｙ ,2 0 0 0 ,Ｎｏ .3)2　Ａｔｍｏｓｐｈｅｒｉｃｉｎｆｒａｓｏｕｎｄ (ＡｌｆｒｅｄＪ .ＢｅｄａｒｄＪｒ ,ＴｈｏｍａｓＭ .Ｇｅｏｒｇｅｓ.Ｐｈｙｓ.Ｔｏｄａｙ ,2 0 0 0 ,Ｎｏ .3)3　Ｌｉｑｕｉｄｃｒｙｓｔａｌｓａｎｄｃａｒｂｏｎｍａｔｅｒｉａｌｓ(ＲｏｂｅｒｔＨ .Ｈｕｒｔ,Ｚｈｏｎｇ ＹｉｎｇＣｈｅｎ .Ｐｈｙｓ.Ｔｏｄａｙ ,…     

低温物理学报第23卷2001 总目录

第 1期Ｌａ2 / 3 Ｃａ1/ 3 ＭｎＯ3 中绝缘体 金属相变与ＣＭＲ效应刘宁　孙勇　童伟　张裕恒 (1)…………………………………………高温超导体的非线性物质方程与涡旋相变齐志　尹道乐 (6 )……………………………………………………………熔融织构ＹＢＣＯ块材和Ｂｉ 2 2 2 3/Ａｇ带材磁光图像研究的评述高政祥　 (14)…………………………………………………理想Ⅱ类超导体在相变点的体积效应俞建群　徐政　王锋　金新　 (2 8)…………………………………………………Ｌａ2 -ｘＢａｘＣｕＯ4 -ｙ单晶样品的制备李鹏程　杨宏顺　任治安　…     

BOPUXUE ZAZHI(CHINESE JOURNAL OF MAGNETIC RESONANCE)GENERAL CONTENTS

Ｖｏｌ.19　Ｎｏ .1　Ｍａｒ.2 0 0 21Ｈ ＭＲＳＳｔｕｄｙｏｆｔｈｅＭｅｔａｂｏｌｉｔｅｏｎｔｈｅＢｏｒｄｅｒＺｏｎｅｏｆＡｃｕｔｅＣｅｒｅｂｒａｌＩｓｃｈｅｍｉａＹＩＬｉ,ＬＵＧｕａｎｇ ,ＬＩＵＭａｉ ｌｉｅｔａｌ.　　 ( 1 -7)…………………………………2ＤＮＭＲＳｔｕｄｙｏｎＰｈｏｔｏｌｙｓｔｉｃＰｒｏｄｕｃｔｓｏｆ 2 ｍｅｔｈｙｌ ｎａｐｈｔｈｏｑｕｉｎｏｎｅＤｉａｚｉｄｅｉｎＣｙｃｌｉｃＥｔｈｅｒｓ ＺＨＡＮＧＷｅｉ,ＬＩＵＺｈｏｎｇ ｌｉ,ＹＡＮＧＬｉ　 ( 9-1 4 )………………ＴｈｅＳｐｅｃｔｒｏｓ…     

在织构Ag基带上制备YBa2Cu3O7-δ超导膜

在织构Ａｇ基带上用脉冲激光方法沉积ＹＢａ２Ｃｕ３Ｏ７－δ超导膜,直流电阻法测量超导膜的临界电流密度为４×１０＾５Ａ／ｃｍ＾２。结合生成膜的结构分析,对ＹＢａ２Ｃｕ３Ｏ７－δ超导体在Ａｇ基带上的生长机制进行讨论。     

Critical depletion

Depletion interactions and the critical Casimir effect are usually regarded as distinct phenomena in colloidal suspensions. By experimentally investigating how the Asakura-Oosawa picture, appropriate for a weakly correlated depletant, is modified when critical correlations develop within the depletion agent, we conversely show that the former merges continuously into the latter, leading to a distinctive scaling behavior solely dictated by the depletant correlation length. A model based on density functional theory provides a microscopic understanding of the phenomenon and properly accounts for the observed trends.     

Critical foliations

Critical foliations are special two-dimensional slices (planes of observation) of a three-dimensional optical field in which an infinitesimally small change in the angle of observation produces major qualitative differences in the observed field structure. They are common, but previously unrecognized, features of optical fields that contain vortices. An experimentally realizable, on-axis example of such a foliation is described for a paraxial Gaussian laser beam.     

Critical ruptures

The fracture of materials is a catastrophic phenomenon of considerable technological and scientific importance. Here, we analysed experiments designed for industrial applications in order to test the concept that, in heterogeneous materials such as fiber composites, rocks, concrete under compression and materials with large distributed residual stresses, rupture is a genuine critical point, i.e., the culmination of a self-organization of damage and cracking characterized by power law signatures. Specifically, we analyse the acoustic emissions recorded during the pressurisation of spherical tanks of kevlar or carbon fibers pre-impregnated in a resin matrix wrapped up around a thin metallic liner (steel or titanium) fabricated and instrumented by Aérospatiale-Matra Inc. These experiments are performed as part of a routine industrial procedure which tests the quality of the tanks prior to shipment. We find that the seven acoustic emission recordings of seven pressure tanks which was brought to rupture exhibit clear acceleration in agreement with a power law “divergence” expected from the critical point theory. In addition, we find strong evidence of log-periodic corrections that quantify the intermittent succession of accelerating bursts and quiescent phases of the acoustic emissions on the approach to rupture. An improved model accounting for the cross-over from the non-critical to the critical region close to the rupture point exhibits interesting predictive potential. Received 6 July 2000     

Critical brain networks

Highly correlated brain dynamics produces synchronized states with no behavioral value, while weakly correlated dynamics prevents information flow. We discuss the idea put forward by Per Bak that the working brain stays at an intermediate (critical) regime characterized by power-law correlations.     

Critical Mandelbrot Cascades

We study Mandelbrot’s multiplicative cascade measures at the critical temperature. As has been recently shown by Barral et al. (C R Acad Sci Paris Ser I 350:535–538, 2012), an appropriately normalized sequence of cascade measures converges weakly in probability to a nontrivial limit measure. We prove that these limit measures have no atoms and give bounds for the modulus of continuity of the cumulative distribution function of the measure. Using the earlier work of Barral and Seuret (Adv Math 214:437–468, 2007), we compute the multifractal spectrum of the measures. We also extend the result of Benjamini and Schramm (Commun Math Phys 289:653–662, 2009), in which the KPZ formula from quantum gravity is validated for the high temperature cascade measures, to the critical and low temperature cases.     

Fundamental Critical Relations

We consider systems which exhibit typical critical dependence of the specific heat: <artwork name="GPHT31001ei1">) where γ, γ ′ are critical exponents (γ = α for <artwork name="GPHT31001ei2"> for <artwork name="GPHT31001ei3">), as well as, the case when <artwork name="GPHT31001ei4">, uniaxial ferroelectrics; a = 1, liquid He⁴). Starting from the critical behaviour of the specific heat we can exactly find the asymptotic form of the Gibbs (Helmholtz) potential in the vicinity of the critical point for each case separately. We derive in this way many exact critical relations in the limit T → T_C which remain the same for each particular case. They define a new class of universal critical relations independent from the underlying microscopic mechanism and the symmetry of these systems. It, however, means that they are independent from the critical indices, characterizing each particular material. The derived relations are valid for magnetic, ferroelectric and superconducting materials, as well as, for liquid He⁴ and they have very important consequences concerning the mutual relations between critical amplitudes of many thermodynamical quantities near the critical point and therefore can be important and interesting from the experimental and technological point of view.     

有限核多重碎裂中的临界行为与临界指数的提取

利用非对称核物质状态方程可以得到有限核¹¹²Sn的压强－密度等温线, 并对其在坐标和动量空间中的分布进行了模拟, 采用了并合模型对形成的核碎片进行了构造. 通过碎片的关联分析, 寻找出了临界行为的信号, 提取了临界指数.