Philosophical Magazine Part B最新文献_第5页

Confined growth of Eu2O3 nanocrystals in a new polymorph in amorphous mesoporous Al2O3 Eu2O3纳米晶在非晶介孔Al2O3中受限生长

Philosophical Magazine Part B Pub Date : 2002-07-01 DOI: 10.1080/13642810208223154

P. Mohanty, S. Ram

引用次数: 8

Contact potential measurements with a local Kelvin probe 接触电位测量与局部开尔文探针

Philosophical Magazine Part B Pub Date : 2002-07-01 DOI: 10.1080/13642810208223162

A. Hadjadj, B. Equer, A. Beorchia, P. Cabarrocas

引用次数: 7

Electrical resistivity and thermoelectric power of molten gallium: Theory versus experiment 熔融镓的电阻率和热电功率:理论与实验

Philosophical Magazine Part B Pub Date : 2002-07-01 DOI: 10.1080/13642810208223160

L. Ben Hassine, J. Auchet, J. Gasser

{"title":"Electrical resistivity and thermoelectric power of molten gallium: Theory versus experiment","authors":"L. Ben Hassine, J. Auchet, J. Gasser","doi":"10.1080/13642810208223160","DOIUrl":"https://doi.org/10.1080/13642810208223160","url":null,"abstract":"Abstract We present our new accurate measurements on the electrical resistivity and thermopower of liquid gallium as a function of temperature. To interpret our experimental data we used, for the first time to our knowledge (earlier calculations used the pseudopotential formalism), ab initio calculations of the electrical resistivity ρ(E) and of the thermoelectric power Q(E) of liquid gallium as functions of energy. This formalism has the great advantage of including a full-energy dependent calculation of the thermopower. To construct the phase shifts we used the experimental pair correlation function. To calculate the resistivity and thermopower we used both the structure factor obtained experimentally and that calculated with hard spheres. The results are compared and discussed. Various potentials based on the Hartree-Fock formalism and using different exchange contributions have been used. Overall agreement between calculation and experiment is obtained. It seems, however, that the Kohn-Sham value of the X-α Slater approximation gives results closer to experiment than the Slater value for both resistivity and thermopower. Subsequently, the problem of the sign of the thermopower of liquid metals is discussed and explained.","PeriodicalId":20016,"journal":{"name":"Philosophical Magazine Part B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84998969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Exchange-based noise spectroscopy of a single precessing spin with scanning tunnelling microscopy 用扫描隧道显微镜研究单进动自旋的交换噪声光谱

Philosophical Magazine Part B Pub Date : 2002-06-17 DOI: 10.1080/13642810208223166

A. Balatsky, Y. Manassen, R. Salem

{"title":"Exchange-based noise spectroscopy of a single precessing spin with scanning tunnelling microscopy","authors":"A. Balatsky, Y. Manassen, R. Salem","doi":"10.1080/13642810208223166","DOIUrl":"https://doi.org/10.1080/13642810208223166","url":null,"abstract":"Abstract Electron spin resonance-scanning tunnelling microscopy is an emerging technique which is capable of detecting the precession of a single spin. We discuss a mechanism based on direct exchange coupling between the tunnelling electrons and the local precessing spin S. We claim that, since the number of tunnelling electrons in a single precessing period is small (about 20), one may expect a net temporary polarization within this period which will couple via exchange interaction to the localized spin. This coupling will modulate the tunnelling barrier with the Larmor frequency of the precessing spin ωL. This modulation, although randomly changing from cycle to cycle, will produce an elevated noise in the current at ωL. We find that for relevant values of parameters the signal-to-noise ratio in the spectral characteristic is 2–4 and is comparable with the values of the signal-to-noise ratio reported by Manassen and co-workers and by Durkan and Welland. The magnitude of the current fluctuation is a relatively weak increasing function of the dc and the magnetic field. The linewidth produced by the back action effect of tunnelling electrons on the precessing spin is also discussed.","PeriodicalId":20016,"journal":{"name":"Philosophical Magazine Part B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79923445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 17

Experimental and computational study of field emission characteristics from amorphous carbon single nanotips grown by carbon contamination II. Theory 碳污染生长非晶碳单纳米尖场发射特性的实验与计算研究[j]。理论

Philosophical Magazine Part B Pub Date : 2002-06-01 DOI: 10.1080/13642810208218358

C. Edgcombe

引用次数: 10

Aspects of magnetotunnelling drawn from ab-initio-type calculations 从ab-initio型计算中得出的磁隧效应的各个方面

Philosophical Magazine Part B Pub Date : 2002-06-01 DOI: 10.1080/13642810208218359

P. Weinberger, V. Drchal, J. Kudrnovský, I. Turek, H. Herper, L. Szunyogh, C. Sommers

{"title":"Aspects of magnetotunnelling drawn from ab-initio-type calculations","authors":"P. Weinberger, V. Drchal, J. Kudrnovský, I. Turek, H. Herper, L. Szunyogh, C. Sommers","doi":"10.1080/13642810208218359","DOIUrl":"https://doi.org/10.1080/13642810208218359","url":null,"abstract":"Abstract Tunnelling between two semi-infinite ferromagnetic electrodes separated by vacuum is studied theoretically on an ab-initio level by using the fully relativistic spin-polarized screened Korringa-Kohn-Rostoker and the spin-polarized non-relativistic tight-binding linear muffin-tin orbital method. The Kubo-Greenwood equation is employed to calculate the non-local conductivity and layer-resolved sheet resistances; the transmission matrix formulation in turn is used to evaluate the conductance. We show that the dependence of sheet resistance on the imaginary part of the Fermi energy allows us to distinguish between the tunnelling and conductive regimes of electron transport. Our numerical studies of the system bcc Fe(100)/vacuum/bcc Fe(100) show quite dramatic variations in the electrostatic potential in the vacuum region and a gradual development of the tunnelling barrier with increasing thickness of the vacuum barrier. Varying the Madelung potential in the interior of the vacuum barrier allowed us to simulate spacers made of semiconducting or insulating material and to discuss the conditions for the presence of a magnetoresistance in such multilayers. As far as the thickness of the vacuum barrier is concerned the results obtained with the transmission matrix approach for fee Co(001)/vacuum/fee Co(001) show a similar tendency to those obtained within the Kubo-Greenwood equation for bcc Fe(100)/vacuum/bcc Fe(100); asymptotically, that is with increasing thickness of the vacuum barrier, the magnetoresistance tends to zero.","PeriodicalId":20016,"journal":{"name":"Philosophical Magazine Part B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73281351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

High-resolution electron microscopy and microanalysis of ordered arrays of size-controlled amorphous gallium nitride nanoparticles synthesized in situ in a block copolymer matrix 在嵌段共聚物基体中原位合成的尺寸控制的非晶态氮化镓纳米颗粒有序阵列的高分辨率电子显微镜和微观分析

Philosophical Magazine Part B Pub Date : 2002-06-01 DOI: 10.1080/13642810208218360

V. Leppert, A. Murali, S. Risbud, M. Stender, P. Power, C. Nelson, P. Banerjee, A. Mayes

{"title":"High-resolution electron microscopy and microanalysis of ordered arrays of size-controlled amorphous gallium nitride nanoparticles synthesized in situ in a block copolymer matrix","authors":"V. Leppert, A. Murali, S. Risbud, M. Stender, P. Power, C. Nelson, P. Banerjee, A. Mayes","doi":"10.1080/13642810208218360","DOIUrl":"https://doi.org/10.1080/13642810208218360","url":null,"abstract":"Abstract The objective of this work was to produce an ordered array of size-controlled gallium nitride (GaN) nanoparticles. The synthesis was performed by the in situ formulation and subsequent decomposition of cyclotrigallazane in a polystyrene (PS)-b-poly(4-vinylpyridine) (b-P4VP) block copolymer matrix. The matrix served as a templating medium to constrain the particle size and to allow the control of particle morphology, spacing and packing arrangement. The size and spacing of nanoparticles were controlled by the molecular weight of the entire polymer chain (81 000g mol−1), and the particle morphology and packing arrangement were controlled by the ratio of the sequestering block to the matrix block (21 wt% P4VP to 79 wt% PS by elemental analysis). High-resolution and analytical transmission electron microscopy revealed the amorphous nanoparticles to be composed mainly of gallium and nitrogen (with oxygen detected in some particles) about 10nm in diameter with an average interparticle distance of 60 nm and organized in a regular hexagonal packing arrangement. The impact of this synthesis technique is to afford the means to investigate systematically the effect of quantum confinement and quantum coupling on the optical properties of small GaN particles.","PeriodicalId":20016,"journal":{"name":"Philosophical Magazine Part B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91185545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Experimental and computational study of field emission characteristics from amorphous carbon single nanotips grown by carbon contamination. I. Experiments and computation 碳污染生长的非晶碳单纳米尖场发射特性的实验与计算研究。一、实验与计算

Philosophical Magazine Part B Pub Date : 2002-06-01 DOI: 10.1080/13642810208218357

C. Edgcombe, U. Valdré

{"title":"Experimental and computational study of field emission characteristics from amorphous carbon single nanotips grown by carbon contamination. I. Experiments and computation","authors":"C. Edgcombe, U. Valdré","doi":"10.1080/13642810208218357","DOIUrl":"https://doi.org/10.1080/13642810208218357","url":null,"abstract":"Abstract Some properties of electron field emitters based on various types of carbon are difficult to measure and are not well known. This is particularly true for amorphous carbon films, for nanotubes and for nanotips grown by carbon contamination in a scanning electron microscope. We show that by combining together experimental data (i.e. emitter geometry from electron microscopy observations, and field emission current and applied voltage measurements), numerically computed values of the electric field at the tip surface and the Fowler-Nordheim (F-N) equation, it is possible to estimate values of parameters such as the work function, the enhancement factor, the tip radius and the effective emitting area. The general applicability of this approach and corresponding results are emphasized. We also show that, when the experimental parameters that are known are superfluous in number (i.e. more than the minimum number needed), a discrepancy exists, firstly, between the value of the emitter radius worked out through the F-N equation and that derived from electron microscopy and, secondly, between the calculated work function and that independently obtained by Kelvin probe microscopy. Possible reasons for these discrepancies are put forward and discussed.","PeriodicalId":20016,"journal":{"name":"Philosophical Magazine Part B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76862452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 41

Explanation of high-temperature superconductivity without cuprate planes 无铜面高温超导现象的解释

Philosophical Magazine Part B Pub Date : 2002-06-01 DOI: 10.1080/13642810208218361

J. Dow, D. R. Harshman

引用次数: 7

Ab initio calculation of the stability of one-dimensional long-period structures in the Cu3Pd compound Cu3Pd化合物一维长周期结构稳定性的从头计算

Philosophical Magazine Part B Pub Date : 2002-06-01 DOI: 10.1080/13642810208218362

C. Colinet, A. Pasturel

引用次数: 2