PhysicaPub Date : 1974-12-01DOI: 10.1016/0031-8914(74)90066-4
C. Huang , A. Van Der Ziel
{"title":"Diffusion noise in double injection diodes","authors":"C. Huang , A. Van Der Ziel","doi":"10.1016/0031-8914(74)90066-4","DOIUrl":"10.1016/0031-8914(74)90066-4","url":null,"abstract":"<div><p>A survey is given of calculations on diffusion noise in double injection SCL diodes. A general asymptotic method applicable to ωτ ⪢ 1 is presented that gives thermal noise at all points in the device. The method of Zijlstra and Gisolf is shown to be non-applicable to the semiconductor regime. For the insulator regime it does not seem to give thermal noise at all points in the device. The method of variation of parameters, when applied to the semiconductor regime, leads to a solution with an unknown integration constant; when this integration constant is chosen zero, one obtains thermal noise plus a g-r like diffusion noise term. Finally an approach is made for the semiconductor regime that does not neglect diffusion. The device then gives thermal noise at all frequencies and at all points in the device, plus a g-r like noise term that is negligible for long devices but noticeable for small ones.</p></div>","PeriodicalId":55605,"journal":{"name":"Physica","volume":"78 2","pages":"Pages 220-232"},"PeriodicalIF":0.0,"publicationDate":"1974-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0031-8914(74)90066-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84245138","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}
PhysicaPub Date : 1974-12-01DOI: 10.1016/0031-8914(74)90065-2
E. Simanek, J.C. Hayward
{"title":"Superconducting fluctuations and tunneling anomalies below Tc","authors":"E. Simanek, J.C. Hayward","doi":"10.1016/0031-8914(74)90065-2","DOIUrl":"10.1016/0031-8914(74)90065-2","url":null,"abstract":"<div><p>The theory of pair tunneling current due to superconducting fluctuations is generalized to include the effects of self-induced a.c. voltage. A new contribution to the d.c. <em>I–V</em> characteristics is found which contains a peak at the value of eV equal to the superconducting order parameter and which explains the secondary peak observed previously.</p></div>","PeriodicalId":55605,"journal":{"name":"Physica","volume":"78 2","pages":"Pages 199-219"},"PeriodicalIF":0.0,"publicationDate":"1974-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0031-8914(74)90065-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76534056","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}
PhysicaPub Date : 1974-12-01DOI: 10.1016/0031-8914(74)90072-X
H.W.J. Blöte
{"title":"The heat capacities of linear Heisenberg chains","authors":"H.W.J. Blöte","doi":"10.1016/0031-8914(74)90072-X","DOIUrl":"10.1016/0031-8914(74)90072-X","url":null,"abstract":"<div><p>The heat capacities of finite chains of magnetic spins <span><math><mtext>1</mtext><mtext>2</mtext></math></span>, 1, <span><math><mtext>3</mtext><mtext>2</mtext></math></span>, 2, and <span><math><mtext>5</mtext><mtext>2</mtext></math></span> with Heisenberg interaction were calculated exactly as a function of temperature. From these data the heat capacities of infinitely long chains were obtained by extrapolation. Further, the antiferromagnetic ground-state energies were estimated.</p></div>","PeriodicalId":55605,"journal":{"name":"Physica","volume":"78 2","pages":"Pages 302-307"},"PeriodicalIF":0.0,"publicationDate":"1974-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0031-8914(74)90072-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79398598","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}
PhysicaPub Date : 1974-12-01DOI: 10.1016/0031-8914(74)90073-1
S. Merchant, J.N. McElearney, G.E. Shankle, R.L. Carlin
{"title":"Two anisotropic Heisenberg linear chain manganese compounds","authors":"S. Merchant, J.N. McElearney, G.E. Shankle, R.L. Carlin","doi":"10.1016/0031-8914(74)90073-1","DOIUrl":"10.1016/0031-8914(74)90073-1","url":null,"abstract":"<div><p>The specific heat and zero-field magnetic susceptibilities of [(CH<sub>3</sub>)<sub>3</sub>NH] MnX<sub>3</sub>.2H<sub>2</sub>O (X=Cl Br) are reported. The isotropic Heisenberg model for linear chains offers a reasonable fit to the data, but a substantial anisotropy is also observed. For the chloride, <em>T</em><sub>N</sub> = 0.98 K, <em>J/k</em> = -0.36 K, and <em>zJ′/k</em> = -0.55 K; for the bromide, <em>T</em><sub>N</sub> = 1.56 K, <em>J/k</em> = -0.41 K, and <em>zJ′/k</em> = -0.74 K. A canted antiferromagnetic structure is proposed.</p></div>","PeriodicalId":55605,"journal":{"name":"Physica","volume":"78 2","pages":"Pages 308-313"},"PeriodicalIF":0.0,"publicationDate":"1974-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0031-8914(74)90073-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81981556","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}
PhysicaPub Date : 1974-12-01DOI: 10.1016/0031-8914(74)90068-8
L.J. Campbell
{"title":"Superfluid flow through multiply connected geometries","authors":"L.J. Campbell","doi":"10.1016/0031-8914(74)90068-8","DOIUrl":"10.1016/0031-8914(74)90068-8","url":null,"abstract":"<div><p>For conditions opposite those considered by Van Alphen <em>et al</em>., the equations for superfluid flow between two reservoirs joined by multiple parallel paths are presented and solved for the case of two paths. Significant circulation (persistent current) can be created and detected by fluid transfer between reservoirs without external control over the flow paths. Characteristic signatures of circulation that are present in the level oscillations are derived in terms of the system parameters. The types of unexplained frequency shifts and damping maxima observed by Hammel <em>et al.</em> in U-tube oscillations are shown to result from a parallel flow path of relatively small area.</p></div>","PeriodicalId":55605,"journal":{"name":"Physica","volume":"78 2","pages":"Pages 245-258"},"PeriodicalIF":0.0,"publicationDate":"1974-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0031-8914(74)90068-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75074426","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}
PhysicaPub Date : 1974-12-01DOI: 10.1016/0031-8914(74)90070-6
Satya Prakash, Natthi Singh
{"title":"A model calculation of susceptibility function of paramagnetic nickel","authors":"Satya Prakash, Natthi Singh","doi":"10.1016/0031-8914(74)90070-6","DOIUrl":"10.1016/0031-8914(74)90070-6","url":null,"abstract":"<div><p>The wave-vector dependent susceptibility function of paramagnetic nickel is investigated using a noninteracting band model which is based on the APW band-structure calculations of Hanus. The effect of exchange enhancement of the susceptibility function is also studied. The results are found in good agreement with other existing theoretical calculations.</p></div>","PeriodicalId":55605,"journal":{"name":"Physica","volume":"78 2","pages":"Pages 273-290"},"PeriodicalIF":0.0,"publicationDate":"1974-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0031-8914(74)90070-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80769116","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}
PhysicaPub Date : 1974-12-01DOI: 10.1016/0031-8914(74)90069-X
J.J. Hallers, T. Mariën, W. Van der Lugt
{"title":"Resistivity calculations for liquid Na-Cs and K-Cs alloy systems","authors":"J.J. Hallers, T. Mariën, W. Van der Lugt","doi":"10.1016/0031-8914(74)90069-X","DOIUrl":"10.1016/0031-8914(74)90069-X","url":null,"abstract":"<div><p>The resistivities of liquid Na-Cs alloys are calculated as a function of the composition. A version of the Heine-Abarenkov model potential is used with special attention to three corrections: first, concentration-dependent core shifts are introduced, secondly, effective masses are taken into account and thirdly, many-electron effects are included by taking the Toigo and Woodruff dielectric function. For the partial structure factors of the alloys the solutions of the Percus-Yevick equations for a binary mixture of hard spheres are applied. The discrepancy between theoretical and experimental values is of the order of twenty percent.</p></div>","PeriodicalId":55605,"journal":{"name":"Physica","volume":"78 2","pages":"Pages 259-272"},"PeriodicalIF":0.0,"publicationDate":"1974-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0031-8914(74)90069-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77282582","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}
PhysicaPub Date : 1974-12-01DOI: 10.1016/0031-8914(74)90071-8
M. Mohajeri, H.A. Rafizadeh
{"title":"The nth-order elastic constants of centrosymmetric ionic solids","authors":"M. Mohajeri, H.A. Rafizadeh","doi":"10.1016/0031-8914(74)90071-8","DOIUrl":"10.1016/0031-8914(74)90071-8","url":null,"abstract":"<div><p>Expressions for the <em>n</em>th-order elastic constants of ionic centrosymmetric solids have been developed using a central crystal-potential expansion. The comparison of the Coulomb contribution to the third-order elastic constants of alkali halides with calculations of Nran'yan and Ghate show disagreements as large as 139%. It is shown that the disagreements may be due to the poor convergence of the Coulomb sums in the previous calculations.</p></div>","PeriodicalId":55605,"journal":{"name":"Physica","volume":"78 2","pages":"Pages 291-301"},"PeriodicalIF":0.0,"publicationDate":"1974-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0031-8914(74)90071-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89786583","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}
{"title":"Heat capacity of [(CH3)3NH] CuCl3.2H2O below 1 K","authors":"H.A. Algra, L.J. de Jongh, H.W.J. Blöte, W.J. Huiskamp, R.L. Carlin","doi":"10.1016/0031-8914(74)90074-3","DOIUrl":"10.1016/0031-8914(74)90074-3","url":null,"abstract":"<div><p>Specific-heat data on [(CH<sub>3</sub>)<sub>3</sub>NH] CuCl<sub>3</sub>.2H<sub>2</sub>O below 1 K are reported. The results agree qualitatively with a model of weakly coupled, ferromagnetic Heisenberg chains. A λ-type anomaly, indicating the onset of long-range order is found at <em>T <sub>c</sub></em> = 0.165 ± 0.005 K.</p></div>","PeriodicalId":55605,"journal":{"name":"Physica","volume":"78 2","pages":"Pages 314-318"},"PeriodicalIF":0.0,"publicationDate":"1974-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0031-8914(74)90074-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76222803","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}
PhysicaPub Date : 1974-12-01DOI: 10.1016/0031-8914(74)90075-5
S.R. Sreenivasan , D.L. Thompson
{"title":"Velocity fields which preserve cylindrically symmetric force-free magnetic fields","authors":"S.R. Sreenivasan , D.L. Thompson","doi":"10.1016/0031-8914(74)90075-5","DOIUrl":"10.1016/0031-8914(74)90075-5","url":null,"abstract":"<div><p>It is shown that constant-α force-free magnetic fields are very preserved by velocity fields satisfying an equation of the form ∇ × <em>ξ</em> = <em>αξ</em>, where <span><math><mtext>ξ = ∇ × (</mtext><mtext>v</mtext><mtext> × </mtext><mtext>B</mtext><mtext>) = (</mtext><mtext>∂</mtext><mtext>∂</mtext><mtext>t</mtext><mtext> − λ∇</mtext><msup><mi></mi><mn>2</mn></msup><mtext>) </mtext><mtext>B</mtext></math></span>, and <span><math><mtext>λ = </mtext><mtext>1</mtext><mtext>μσ</mtext></math></span>. Explicit expressions are derived for the velocity fields preserving cylindrically symmetric force-free magnetic fields of interest in controlled thermonuclear fusion studies as well as astrophysics. Such velocity fields include the form of observed astrophysical features reported in the literature as well as those invoked in other studies, thus lending them further support and a firm foundation.</p></div>","PeriodicalId":55605,"journal":{"name":"Physica","volume":"78 2","pages":"Pages 321-339"},"PeriodicalIF":0.0,"publicationDate":"1974-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0031-8914(74)90075-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79747841","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}
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