排序方式: 共有38条查询结果,搜索用时 15 毫秒
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We have made Meservey-Tedrow style spin-polarized tunneling measurements on SrRuO3, using a SrTiO3 barrier. In contrast to all other materials measured with this technique, we found the spin polarization to be negative, P = -9.5%. This makes it possible to test the generalized Julliere model for a negatively spin-polarized electrode, by measuring the magnetoresistance of a La(0.7)Sr(0. 3)MnO(3)/SrTiO(3)/SrRuO(3) tunnel junction. The generalized Julliere theory predicts it should be inverse. 相似文献
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Low temperature heat capacity and electrical resistivity measurements are reported for ReO3. The heat capacity data give an acoustical mode Debye temperature θ = 327 K, and an electrronic density of states parameter γ = 2.83 mJ/mole-K2. The observed temperature dependence of the resistivity is consistent with the existence of electron scattering both from acoustic mode phonons and from optical mode phonons of characteristic temperature θE = 1080 K. The above measurements are used to evaluate the electron-phonon interaction parameter λ = 0.24. 相似文献
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Muddana HS Varnado CD Bielawski CW Urbach AR Isaacs L Geballe MT Gilson MK 《Journal of computer-aided molecular design》2012,26(5):475-487
The computational prediction of protein-ligand binding affinities is of central interest in early-stage drug-discovery, and there is a widely recognized need for improved methods. Low molecular weight receptors and their ligands--i.e., host-guest systems--represent valuable test-beds for such affinity prediction methods, because their small size makes for fast calculations and relatively facile numerical convergence. The SAMPL3 community exercise included the first ever blind prediction challenge for host-guest binding affinities, through the incorporation of 11 new host-guest complexes. Ten participating research groups addressed this challenge with a variety of approaches. Statistical assessment indicates that, although most methods performed well at predicting some general trends in binding affinity, overall accuracy was not high, as all the methods suffered from either poor correlation or high RMS errors or both. There was no clear advantage in using explicit versus implicit solvent models, any particular force field, or any particular approach to conformational sampling. In a few cases, predictions using very similar energy models but different sampling and/or free-energy methods resulted in significantly different results. The protonation states of one host and some guest molecules emerged as key uncertainties beyond the choice of computational approach. The present results have implications for methods development and future blind prediction exercises. 相似文献
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H.P. Fredricksen H.L. Salvo M. Levy R.H. Hammond T.H. Geballe 《Physics letters. A》1980,75(5):389-391
The attenuation of 660 MHz surface acoustic waves propagating in a thin film of Nb3Sn 5000 Å thick has been measured as a function of temperature from 4.2 K to 16 K. The A 15 Nb3Sn, electron-beam codeposited on YZ lithium niobate and annealed at 700°C, was studied using 5.1 μm wavelength interdigital electrodes. The film revealed a transition temperature of 14.2 ± 0.1 K and using the BCS theory, an energy gap 2Δ(0) = 3.5 kBTc. 相似文献
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G.S. Brown L.R. Testardi J.H. Wernick A.B. Hallak T.H. Geballe 《Solid State Communications》1977,23(12):875-878
We have measured the Extended X-ray Absorption Fine Structure (EXAFS) spectra for superconducting thin films of Nb3Ge prepared at variable deposition temperature by sputtering and electron beam coevaporation. As the deposition temperature is varied from 1050 K to 875 K, the film structure changes continuously from the A15 phase to a quasi-amorphous phase. This amorphous phase is characterized by a mean Ge-Nb distance of 2.66 A, as compared to the A15 distance, 2.87 A. The mean coordination of the Ge sites is reduced from 12 to 8±2, and the mean square spread in Ge-Nb distances (thermal + spatial) has decreased by only 0.01 A2. 相似文献
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Zachary M. Geballe Hanyu Liu Ajay K. Mishra Muhtar Ahart Maddury Somayazulu Yue Meng Maria Baldini Russell J. Hemley 《Angewandte Chemie (International ed. in English)》2018,57(3):688-692
Recent theoretical calculations predict that megabar pressure stabilizes very hydrogen‐rich simple compounds having new clathrate‐like structures and remarkable electronic properties including room‐temperature superconductivity. X‐ray diffraction and optical studies demonstrate that superhydrides of lanthanum can be synthesized with La atoms in an fcc lattice at 170 GPa upon heating to about 1000 K. The results match the predicted cubic metallic phase of LaH10 having cages of thirty‐two hydrogen atoms surrounding each La atom. Upon decompression, the fcc‐based structure undergoes a rhombohedral distortion of the La sublattice. The superhydride phases consist of an atomic hydrogen sublattice with H?H distances of about 1.1 Å, which are close to predictions for solid atomic metallic hydrogen at these pressures. With stability below 200 GPa, the superhydride is thus the closest analogue to solid atomic metallic hydrogen yet to be synthesized and characterized. 相似文献