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Study of Upper Critical Magnetic Field of Superconducting HoMo 6 Se 8 超导HoMo 6 Se 8上临界磁场的研究
World Journal of Condensed Matter Physics Pub Date : 2015-07-27 DOI: 10.4236/WJCMP.2015.53013
Tadesse Desta, Pooran Singh, G. Kahsay
{"title":"Study of Upper Critical Magnetic Field of Superconducting HoMo 6 Se 8","authors":"Tadesse Desta, Pooran Singh, G. Kahsay","doi":"10.4236/WJCMP.2015.53013","DOIUrl":"https://doi.org/10.4236/WJCMP.2015.53013","url":null,"abstract":"This work focuses on the study of mathematical aspects of upper critical magnetic field of superconducting HoMo6Se8. At zero external magnetic field, HoMo6Se8 was found to undergo a transition from the normal state to the superconducting state at 5.6 K and returned to a normal but magnetically ordered state between the temperature range of 0.3 K and 0.53 K. The main objective of this work is to show the temperature dependence of the upper critical magnetic field of superconducting HoMo6Se8 by using the Ginzburg-Landau (GL) phenomenological Equation. We found the direct relationship between the GL coherence length (ξGL) and penetration depth (λGL) with temperature. From the GL Equations and the results obtained for the GL coherence length, the expression for upper critical magnetic field (Hc2) is obtained for the superconducting HoMo6Se8. The result is plotted as a function of temperature. The graph shows the linear dependence of upper critical magnetic field (Hc2) with temperature (T) and our finding is in agreement with experimental observations.","PeriodicalId":308307,"journal":{"name":"World Journal of Condensed Matter Physics","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129529348","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: 1
Polarization and Breakdown Analysis of AlGaN Channel HEMTs with AlN Buffer 带AlN缓冲液的AlGaN通道hemt的极化和击穿分析
World Journal of Condensed Matter Physics Pub Date : 2015-07-27 DOI: 10.4236/WJCMP.2015.53024
Godwin Raj, Mohan Kumar, C. Sarkar
{"title":"Polarization and Breakdown Analysis of AlGaN Channel HEMTs with AlN Buffer","authors":"Godwin Raj, Mohan Kumar, C. Sarkar","doi":"10.4236/WJCMP.2015.53024","DOIUrl":"https://doi.org/10.4236/WJCMP.2015.53024","url":null,"abstract":"We have demonstrated the first carrier density model for AlGaN channel with AlN buffer using spontaneous and piezoelectric polarization comparison with experimental and theoretical results. From the results we proved that the formation of 2DEG in undoped structure relied both on spontaneous and piezoelectric polarization. The electron distribution of Al concentration (0 < x < 0.5) was measured for both AlGaN channel and barrier. Barrier thickness assumed between 20 and 25 nm for validating the experimental results. The carrier concentration was observed at the specific interface of the N- and Ga-face by assuming x1, x2 = 0. The model results are verified with previously reported experimental data.","PeriodicalId":308307,"journal":{"name":"World Journal of Condensed Matter Physics","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116661629","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: 1
Coexistence of Superconductivity and Antiferromagnetism in SmAsO1-xFxFe SmAsO1-xFxFe中超导性和反铁磁性的共存
World Journal of Condensed Matter Physics Pub Date : 2015-07-27 DOI: 10.4236/WJCMP.2015.53016
A. Mebrahtu, P. Singh
{"title":"Coexistence of Superconductivity and Antiferromagnetism in SmAsO1-xFxFe","authors":"A. Mebrahtu, P. Singh","doi":"10.4236/WJCMP.2015.53016","DOIUrl":"https://doi.org/10.4236/WJCMP.2015.53016","url":null,"abstract":"Superconductivity and magnetism have been interesting topics in condensed mater physics and they have been studied experimentally and theoretically for many years. These two cooperative phenomena are antagonistic until the discovery of some rare earth ternary compounds that show the coexistence of superconductivity and magnetism. In some of the recently discovered iron-based layered superconductors, superconductivity and magnetism coexist. In the present work we examine the possibility of coexistence of antiferromagnetism and superconductivity in samarium arsenide oxide superconductor (SmAsO1-xFxFe). Using a model of the Hamiltonian and retarded double time Greens function formalism, we found expressions AFM order Parameter (η) and AFM transition temperature (Tm). We obtained the phase diagrams (Tc vs η) and(Tm vs η) to obtain the region where orders, i.e., superconductivity and AFM (antiferromagnetism), coexisted. The region under the intersection of the two merged graphs shows that superconductivity and AFM coexist in the system (SmAsO1-xFxFe).","PeriodicalId":308307,"journal":{"name":"World Journal of Condensed Matter Physics","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127607779","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: 2
Structure and Dielectric Relaxation Behaviour of [Pb 0.94 Sr 0.06 ][(Mn 1/3 Sb 2/3 ) 0.05 (Zr 0.49 Ti 0.51 ) 0.95 ]O 3 Ceramics [Pb 0.94 Sr 0.06][(Mn 1/3 Sb 2/3) 0.05 (Zr 0.49 Ti 0.51) 0.95] o3陶瓷的结构和介电弛豫行为
World Journal of Condensed Matter Physics Pub Date : 2015-07-27 DOI: 10.4236/WJCMP.2015.53022
Kumar Brajesh, K. Kumari
{"title":"Structure and Dielectric Relaxation Behaviour of [Pb 0.94 Sr 0.06 ][(Mn 1/3 Sb 2/3 ) 0.05 (Zr 0.49 Ti 0.51 ) 0.95 ]O 3 Ceramics","authors":"Kumar Brajesh, K. Kumari","doi":"10.4236/WJCMP.2015.53022","DOIUrl":"https://doi.org/10.4236/WJCMP.2015.53022","url":null,"abstract":"The field dependences of the dielectric response and conductivity are measured in a frequency range from 100 Hz to 1 MHz and in a temperature range from 300 K to about 775 K. The dielectric measurements (real and imaginary parts) of this composition with temperature (300 K - 775 K) at different frequencies (100 Hz - 1 MHz) unambiguously point towards relaxor behaviour of the material. The real part of the dielectric constant is found to decrease with increasing frequency at different temperatures while the position of dielectric loss peak shifts to higher frequencies with increasing temperature indicating a strong dispersion beyond the transition temperature, a feature known for relaxational systems such as dipole glasses. The frequency dependence of the loss peak obeys an Arrhenius law with activation energy of 0.15 eV. The distribution of relaxation times is confirmed by Cole-Cole plots as well as the scaling behavior of the imaginary part of the electric modulus. The frequency-dependent electrical data are also analyzed in the framework of the conductivity and modulus formalisms. Both these formalisms yield qualitative similarities in the relaxation times. The Rietveld analysis conforms that the materials exhibits tetragonal structure. The SEM photographs of the sintered specimens present the homogenous structures and well-grown grains with a sharp grain boundary.","PeriodicalId":308307,"journal":{"name":"World Journal of Condensed Matter Physics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123841568","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: 4
Modeling of a Cubic Antiferromagnetic Cuprate Super-Cage 立方反铁磁铜酸盐超级笼的建模
World Journal of Condensed Matter Physics Pub Date : 2015-07-27 DOI: 10.4236/WJCMP.2015.53018
H. Otto
{"title":"Modeling of a Cubic Antiferromagnetic Cuprate Super-Cage","authors":"H. Otto","doi":"10.4236/WJCMP.2015.53018","DOIUrl":"https://doi.org/10.4236/WJCMP.2015.53018","url":null,"abstract":"Convex polyhedral cuprate clusters are being formed through lateral frustration when the a and c lattice parameters of the tetragonal ACuO2 infinite layer structure will become identical by substitution of a large cation (A = Ba2+). However, the corner-shared CuO2 plaquettes of the infinite network suffer a topotactic rearrangement forming edge-connected units, for instance Cu18O24 cages (polyhedron notation [4641238]) with 2 compound (space group P4/ nmm) will be discussed. The possibility to construct a cuprate super-cage with m3m symmetry (polyhedron notation [4641242438]) is being reported. This super-cage still consists of edge-connected CuO2 plaquettes when fully decorated with copper ions, but with different curvatures, arranged in circles of 9.39 ? of diameter with 139.2° Cu-O-Cu antiferromagnetic super-exchange interaction. On the one hand, the realization of such a quite stable cuprate super-cage as a candidate for high-Tc superconductivity depends on whether a template of suitable size such as the cation or C(CH3)4 enables its formation, and on the other hand the cage can further be stabilized by highly charged cations located along the [111] direction. Synthesis options will be proposed based on suggested cage formation pathways. An X-ray powder pattern was calculated for a less dense cluster structure of Im3m space group with a lattice parameter of a = 14.938 ? and two formula units of Cu46O51 to facilitate future identification. Characteristic X-ray scattering features as identification tool were obtained when the electron distribution of the hollow polyhedron was approximated with electron density in a spherical shell.","PeriodicalId":308307,"journal":{"name":"World Journal of Condensed Matter Physics","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122115425","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: 6
Berry Approach to Intrinsic Anomalous Hall Conductivity in Dilute Magnetic Semiconductors (Ga1−xMnxAs) 稀磁性半导体(Ga1−xMnxAs)中本征异常霍尔电导率的Berry方法
World Journal of Condensed Matter Physics Pub Date : 2015-07-27 DOI: 10.4236/WJCMP.2015.53019
Sintayehu Mekonnen, Pooran Singh
{"title":"Berry Approach to Intrinsic Anomalous Hall Conductivity in Dilute Magnetic Semiconductors (Ga1−xMnxAs)","authors":"Sintayehu Mekonnen, Pooran Singh","doi":"10.4236/WJCMP.2015.53019","DOIUrl":"https://doi.org/10.4236/WJCMP.2015.53019","url":null,"abstract":"We develop a model Hamiltonian to treat intrinsic anomalous Hall conductivity in dilute magnetic semiconductor (DMS) of type (III, Mn, V) and obtain the Berry potential and Berry curvature which are responsible for intrinsic anomalous Hall conductivity in Ga1-x MnxAs DMS. Based on Kubo formalism, we establish the relation between Berry curvature and intrinsic anomalous Hall conductivity. We find that for strong spin-orbit interaction intrinsic anomalous Hall conductivity is quantized which is in agreement with recent experimental observation. In addition, we show that the intrinsic anomalous Hall conductivity (AHC) can be controlled by changing concentration of magnetic impurities as well as exchange field. Since Berry curvature related contribution of anomalous Hall conductivity is believed to be dissipationless, our result is a significant step toward achieving dissipationless electron transport in technologically relevant conditions in emerging of spintronics.","PeriodicalId":308307,"journal":{"name":"World Journal of Condensed Matter Physics","volume":"130 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128524733","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
Violating of the Essam-Fisher and Rushbrooke Relationships at Low Temperatures 低温条件下Essam-Fisher和Rushbrooke关系的违反
World Journal of Condensed Matter Physics Pub Date : 2015-04-01 DOI: 10.4236/WJCMP.2015.52008
V. Udodov
{"title":"Violating of the Essam-Fisher and Rushbrooke Relationships at Low Temperatures","authors":"V. Udodov","doi":"10.4236/WJCMP.2015.52008","DOIUrl":"https://doi.org/10.4236/WJCMP.2015.52008","url":null,"abstract":"The \u0000Essam-Fisher and Rushbrooke relationships (1963) that connect the equilibrium \u0000critical exponents of susceptibility, specific heat and order parameter (and \u0000some other relations that follow from the scaling hypothesis) are shown to be \u0000valid only if the critical temperature TС > 0 and T → TC. For phase transitions (PT’s) with TC = 0 K these relations are proved to be of different form. This fact has \u0000been actually observed experimentally, but the reasons were not quite clear. A \u0000general formula containing the classical results as a special case is proposed. \u0000This formula is applicable to all equilibrium PT’s of any space dimension for \u0000both TC = 0 and TC > 0. The predictions of \u0000the theory are consistent with the available experimental data and do not cast \u0000any doubts upon the scaling hypothesis.","PeriodicalId":308307,"journal":{"name":"World Journal of Condensed Matter Physics","volume":"215 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128777677","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: 4
Electronic and Optical Properties of Rare Earth Oxides: Ab Initio Calculation 稀土氧化物的电子和光学性质:从头计算
World Journal of Condensed Matter Physics Pub Date : 2015-04-01 DOI: 10.4236/WJCMP.2015.52011
S. Horoz, Sevket Simsek, S. Palaz, A. Mamedov
{"title":"Electronic and Optical Properties of Rare Earth Oxides: Ab Initio Calculation","authors":"S. Horoz, Sevket Simsek, S. Palaz, A. Mamedov","doi":"10.4236/WJCMP.2015.52011","DOIUrl":"https://doi.org/10.4236/WJCMP.2015.52011","url":null,"abstract":"In this work, we have investigated the electronic and optical properties of the technologically im- portant rare earth oxide compounds—X2O3 (X: Gd, Tb) using the density functional theory within the GGA. The band structure of X2O3 have been calculated along high symmetry directions in the first brillouin zone. The real and imaginary parts of dilectric functions and the other optical res- ponses such as energy-loss function, the effective number of valence electrons and the effective optical dielectric constants of the rare earth sesquioxides (Gd2O3 and Tb2O3) were calculated.","PeriodicalId":308307,"journal":{"name":"World Journal of Condensed Matter Physics","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122683411","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: 9
System of Potential Barriers in Nanostructures 纳米结构中的势垒系统
World Journal of Condensed Matter Physics Pub Date : 2015-04-01 DOI: 10.4236/WJCMP.2015.52009
A. G. Gulyamov
{"title":"System of Potential Barriers in Nanostructures","authors":"A. G. Gulyamov","doi":"10.4236/WJCMP.2015.52009","DOIUrl":"https://doi.org/10.4236/WJCMP.2015.52009","url":null,"abstract":"Nanoscale superlattice has been investigated theoretically. It has been shown that the deformation effects on the energy spectrum of nanoscale superlattice by changing the interatomic distances as well as varying the width and height of the potential barrier. The potential deformation has been estimated. It has been shown that for different edges of forbidden bands the deformation potential has different values. It has been also analyzed the dependence of the effective mass on energy. It has been determined that the effective mass crosses periodically the zero mark. It has been concluded that this phenomena contributes to the periodic change of the oscillation frequency de Haas-van Alphen effect.","PeriodicalId":308307,"journal":{"name":"World Journal of Condensed Matter Physics","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124259523","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: 2
Pyroelectric Bi 5-x (Bi 2 S 3 ) 39 I 12 S: Fibonacci Superstructure, Synthesis Options and Solar Cell Potential 热释电bi5 -x (bi2s3) 39i12s:斐波那契上层结构、合成选择和太阳能电池电位
World Journal of Condensed Matter Physics Pub Date : 2015-04-01 DOI: 10.4236/WJCMP.2015.52010
H. Otto
{"title":"Pyroelectric Bi 5-x (Bi 2 S 3 ) 39 I 12 S: Fibonacci Superstructure, Synthesis Options and Solar Cell Potential","authors":"H. Otto","doi":"10.4236/WJCMP.2015.52010","DOIUrl":"https://doi.org/10.4236/WJCMP.2015.52010","url":null,"abstract":"Previously, synthetic hexagonal bismuth sulfide iodide (polar space group P63, a = 15.629(3) ?, c = 4.018(1) ?, Z = 2) has been described by the rather unsatisfactory fractional formula Bi19/3IS9 [1]-[3]. A redetermination of the structure using old but reliable photographic intensity data indicated the presence of additional split positions and reduced atomic occupancies. From the observed pattern of this “averaged” structure a consistent model of a superstructure with lattice parameters of a' = √13·a = 56.35(1) ?, c' = c, and a formula Bi5-x(Bi2S3)39I12S emerged, with 2 formula units in a cell of likewise P63 space group. Structural modulation may be provoked by the space the lone electron pair of Bi requires. When Bi on the 0, 0, z position of the “averaged” cell is transferred to two general six-fold sites and one unoccupied twofold one of the super-cell, more structural stability is guaranteed due to compensation of its basal plane dipole momentum. Owing to the limited intensity data available, more details of the superstructure are not accessible yet. Some physical properties and solar cell application are discussed together with suggestions of ambient temperature synthesis routes of c-axis oriented nano-rod sheets.","PeriodicalId":308307,"journal":{"name":"World Journal of Condensed Matter Physics","volume":"150 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116090972","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: 6
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