首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   30篇
  免费   0篇
物理学   30篇
  2013年   2篇
  2010年   1篇
  2008年   1篇
  2007年   1篇
  2006年   2篇
  2005年   2篇
  2004年   1篇
  2002年   4篇
  1996年   1篇
  1994年   7篇
  1993年   3篇
  1992年   2篇
  1989年   1篇
  1985年   1篇
  1980年   1篇
排序方式: 共有30条查询结果,搜索用时 15 毫秒
1.
Ultrathin artificial high temperature superconducting structures, consisting of (Ba(0.9)Nd0.1)CuO2+x and CaCuO2 layers, were grown by pulsed laser deposition. Intralayer superconductivity at 60 K was obtained for a structure consisting of a single (CaCuO2) block sandwiched between two (Ba(0.9)Nd0.1)CuO2+x charge reservoir blocks. The purely intralayer critical current density was measured at 4.2 K and resulted to be larger than 10(8) A/cm(2). These findings clearly show that interaction between nearest neighbor (CaCuO2) layers is not essential for high T(c) superconductivity and strongly supports the physical model based on the idea that intralayer interaction alone is responsible for high temperature superconductivity.  相似文献   
2.
We report the results of Oxygen K-edge soft X-ray absorption and emission spectroscopy that was performed on an infinite-layer insulating cuprate thin film CaCuO2. Experimentally obtained spectra are consistent with local density approximation calculations. X-ray absorption spectra show a close resemblance to spectra obtained from homologous single crystal cuprates. In addition to d–d excitations, X-ray emission spectra reveal the presence of Zhang-Rice singlet states in the infinite-layer CuO2 planes. The question of whether the Zhang-Rice singlet features are masked by the O 2p main-band is addressed: it is possible to quantify the position of the Zhang-Rice singlet using emission intensity profiles. X-ray emission is demonstrated as a tool for understanding CuO2 planar electronic correlation in the prototypical infinite-layer. The energy difference, 2.0 eV, between the oxygen main-band and the Zhang-Rice singlet band is found to match values obtained theoretically using established planar electronic correlation parameters.  相似文献   
3.
Persico  V.  Fontana  F.  Wang  Y. H.  Balestrino  G. 《Il Nuovo Cimento D》1994,16(10):1715-1721
Il Nuovo Cimento D - High-quality single-phase thin platelets of BSCCO-2223 have been produced by a novel method on thermal-gradient-enhanced KCl flux which allows the growth of the 2223-phase in...  相似文献   
4.
The growth of the transverse resistivity just above the transition in Bi2Sr2CaCu2O8+x (BSCCO 2212) expitaxial films is studied in the framework of the recent fluctuation model proposed by Ioffe, Larkin, Varlamov and Yu Lu. The effects of different redox thermal treatments on the transverse resistive peak is investigated. The fit of the experimental curves with the theory is good and allows one to estimate the values of some physical parameters included in the theory itself (namely the in-plane Fermi velocity νF, the carrier lifetime τ and the hopping integral w). It is shown that the oxidizing thermal treatment gives rise to a strong decrease in the transverse resistance peak just above Tc. Such effect is ascribed to the increase in νF due to the growth of the carrier concentration induced by the oxidizing treatment. Effects on the carrier lifetime and the hopping integral are hindered by the large variation of νF.  相似文献   
5.
We use x-ray spectroscopy to examine the electronic structure of high-temperature superconducting superlattices [(Ba0.9Nd0.10)CuO(2 + delta)]2/[CaCuO2]2. The O 2p density of states reveals the insulating character of the individual component layers and the metallic character of the superlattices. We report the first direct observation of Zhang-Rice singlets in artificial high-temperature superconducting heteroepitaxial structures. The experimental findings in the superlattices and its component layers offer evidence of charge transport from the so-called charge reservoir layer to the superconducting infinite layer. This suggests a strong link between superconductivity and both electron correlation and charge transfer within the superlattices.  相似文献   
6.

We propose a Ginzburg-Landau phenomenological model for the dependence of the critical temperature on microscopic strain in tetragonal high-[Formula: See Text] cuprates. Such a model is in agreement with the experimental results for LSCO under epitaxial strain, as well as with the hydrostatic pressure dependence of [Formula: See Text] in most cuprates. In particular, a nonmonotonic dependence of [Formula: See Text] on hydrostatic pressure, as well as on in-plane or apical microstrain, is derived. From a microscopic point of view, such results can be understood as due to the proximity to an electronic topological transition (ETT). In the case of LSCO, we argue that such an ETT can be driven by a strain-induced modification of the band structure, at constant hole content, at variance with a doping-induced ETT, as is usually assumed.  相似文献   
7.
Mössbauer spectroscopy of a silicon substituted YIG containing 0.3 Si4+ per formula unit has shown that a spin reorientation, from [111] to [100], occurs between 265 and 80 K. The transitions occur by way of the magnetic space groups R3c′ → F2′dI41acd. The broad spin reorientation is mainly a consequence of the persistence of a nonuniform distribution of Fe2+ ions over the octahedral sites.  相似文献   
8.
The phenomenological theory broadly applicable to magnetic transitions in ferrimagnetic garnets is discussed briefly. The experimental techniques, particularly nuclear magnetic resonance and Mössbauer effect spectroscopy, are then reviewed. Finally, there is a review of the results on specific garnets which undergo such transitions. Some remaining problems are pointed out.  相似文献   
9.
The reflectivities of seven films belonging to the Bi-Sr-Ca-Cu-O family, with Tc ranging from 60 to 95 K, and of a single crystal of insulating Bi-Sr-Y-Cu-O, have been measured at room temperature in the normal phase. The optical conductivity has been analyzed in terms of Drude (D), mid-infrared (MIR), and charge-transfer (CT) contributions. As Tc increases, the spectral weight within the charge-transfer gap (D+MIR) increases. Meanwhile, the peak frequency of the MIR band moves towards the far-infrared and the optical conductivity becomes more similar to that of a normal metal.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号