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This thesis presents various characteristics of 122-type iron pnictide (FeSC) such as crystal and electronic structure, carrier-doping effect, and impurity-scattering effect, using transport, magnetization, specific heat, single-crystal X-ray diffraction, and optical spectral measurements. Most notably the measurement on the magnetic fluctuation in the material successfully explains already known unusual electronic properties, i.e., superconducting gap symmetry, anisotropy of in-plane resistivity in layered structure, and charge dynamics; and comparing them with those of normal phase, the controversial problems in FeSCs are eventually settled. The thesis provides broad coverage of the physics of FeSCs both in the normal and superconducting phase, and readers therefore benefit from the efficient up-to-date study of FeSCs in this thesis. An additional attraction is the detailed description of the experimental result critical for the controversial problems remaining since the discovery of FeSC in 2008, which helps readers follow up recent developments in superconductor research.
Book Synopsis Study of Electronic Properties of 122 Iron Pnictide Through Structural, Carrier-Doping, and Impurity-Scattering Effects by : Tatsuya Kobayashi
Download or read book Study of Electronic Properties of 122 Iron Pnictide Through Structural, Carrier-Doping, and Impurity-Scattering Effects written by Tatsuya Kobayashi and published by Springer. This book was released on 2017-05-07 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents various characteristics of 122-type iron pnictide (FeSC) such as crystal and electronic structure, carrier-doping effect, and impurity-scattering effect, using transport, magnetization, specific heat, single-crystal X-ray diffraction, and optical spectral measurements. Most notably the measurement on the magnetic fluctuation in the material successfully explains already known unusual electronic properties, i.e., superconducting gap symmetry, anisotropy of in-plane resistivity in layered structure, and charge dynamics; and comparing them with those of normal phase, the controversial problems in FeSCs are eventually settled. The thesis provides broad coverage of the physics of FeSCs both in the normal and superconducting phase, and readers therefore benefit from the efficient up-to-date study of FeSCs in this thesis. An additional attraction is the detailed description of the experimental result critical for the controversial problems remaining since the discovery of FeSC in 2008, which helps readers follow up recent developments in superconductor research.
This volume presents an in-depth review of experimental and theoretical studies on the newly discovered Fe-based superconductors. Following the Introduction, which places iron-based superconductors in the context of other unconventional superconductors, the book is divided into three sections covering sample growth, experimental characterization, and theoretical understanding. To understand the complex structure-property relationships of these materials, results from a wide range of experimental techniques and theoretical approaches are described that probe the electronic and magnetic properties and offer insight into either itinerant or localized electronic states. The extensive reference lists provide a bridge to further reading. Iron-Based Superconductivity is essential reading for advanced undergraduate and graduate students as well as researchers active in the fields of condensed matter physics and materials science in general, particularly those with an interest in correlated metals, frustrated spin systems, superconductivity, and competing orders.
Book Synopsis Iron-Based Superconductivity by : Peter D. Johnson
Download or read book Iron-Based Superconductivity written by Peter D. Johnson and published by Springer. This book was released on 2015-01-06 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents an in-depth review of experimental and theoretical studies on the newly discovered Fe-based superconductors. Following the Introduction, which places iron-based superconductors in the context of other unconventional superconductors, the book is divided into three sections covering sample growth, experimental characterization, and theoretical understanding. To understand the complex structure-property relationships of these materials, results from a wide range of experimental techniques and theoretical approaches are described that probe the electronic and magnetic properties and offer insight into either itinerant or localized electronic states. The extensive reference lists provide a bridge to further reading. Iron-Based Superconductivity is essential reading for advanced undergraduate and graduate students as well as researchers active in the fields of condensed matter physics and materials science in general, particularly those with an interest in correlated metals, frustrated spin systems, superconductivity, and competing orders.
Book Synopsis Journal of the Physical Society of Japan by :
Download or read book Journal of the Physical Society of Japan written by and published by . This book was released on 2016 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Development of silicon based electronics have revolutionized our every day life during the last three decades. Nowadays Si based devices operate close to their theoretical limits that is becoming a bottleneck for further progress. In particular, for the growing field of high frequency and high power electronics, Si cannot offer the required properties. Development of materials capable of providing high current densities, carrier mobilities and high breakdown fields is crucial for a progress in state of the art electronics. Epitaxial graphene grown on semi-insulating silicon carbide substrates has a high potential to be integrated in the current planar device technologies. High electron mobilities and sheet carrier densities make graphene extremely attractive for high frequency analog applications. One of the remaining challenges is the interaction of epitaxial graphene with the substrate. Typically, much lower free charge carrier mobilities, compared to free standing graphene, and doping, due to charge transfer from the substrate, is reported. Thus, a good understanding of the intrinsic free charge carriers properties and the factors affecting them is very important for further development of epitaxial graphene. III-group nitrides have been extensively studied and already have proven their high efficiency as light sources for short wavelengths. High carrier mobilities and breakdown electric fields were demonstrated for III-group nitrides, making them attractive for high frequency and high power applications. Currently, In-rich InGaN alloys and AlGaN/GaN high electron mobility structures are of high interest for the research community due to open fundamental questions. Electrical characterization techniques, commonly used for the determination of free charge carrier properties, require good ohmic and Schottky contacts, which in certain cases can be difficult to achieve. Access to electrical properties of buried conductive channels in multilayered structures requires modification of samples and good knowledge of the electrical properties of all electrical contact within the structure. Moreover, the use of electrical contacts to electrically characterize two-dimensional electronic materials, such as graphene, can alter their intrinsic properties. Furthermore, the determination of effective mass parameters commonly employs cyclotron resonance and Shubnikov-de Haas oscillations measurements, which require long scattering times of free charge carriers, high magnetic fields and low temperatures. The optical Hall effect is an external magnetic field induced optical anisotropy in conductive layers due to the motion of the free charge carriers under the influence of the Lorentz force, and is equivalent to the electrical Hall effect at optical frequencies. The optical Hall effect can be measured by generalized ellipsometry and provides a powerful method for the determination of free charge carrier properties in a non-destructive and contactless manner. In principle, a single optical Hall effect measurement can provide quantitative information about free charge carrier types, concentrations, mobilities and effective mass parameters at temperatures ranging from few kelvins to room temperature and above. Further, it was demonstrated that for transparent samples, a backside cavity can be employed to enhance the optical Hall effect. Measurement of the optical Hall effect by generalized ellipsometry is an indirect technique requiring subsequent data analysis. Parameterized optical models are fitted to match experimentally measured ellipsometric data by varying physically significant parameters. Analysis of the optical response of samples, containing free charge carriers, employing optical models based on the classical Drude model, which is augmented with an external magnetic field contribution, provide access to the free charge carrier properties. The main research results of the graduate studies presented in this licentiate thesis are summarized in the five scientific papers. Paper I. Description of the custom-built terahertz frequency-domain spectroscopic ellipsometer at Linköping University. The terahertz ellipsometer capabilities are demonstrated by an accurate determination of the isotropic and anisotropic refractive indices of silicon and m-plane sapphire, respectively. Further, terahertz optical Hall effect measurements of an AlGaN/GaN high electron mobility structures were employed to extract the two-dimensional electron gas sheet density, mobility and effective mass parameters. Last, in-situ optical Hall effect measurement on epitaxial graphene in a gas cell with controllable environment, were used to study the effects of environmental doping on the mobility and carrier concentration. Paper II. Presents terahertz cavity-enhanced optical Hall measurements of the monolayer and multilayer epitaxial graphene on semi-insulating 4H-SiC (0001) substrates. The data analysis revealed p-type doping for monolayer graphene with a carrier density in the low 1012 cm?2 range and a carrier mobility of 1550 cm2/V·s. For the multilayer epitaxial graphene, n-type doping with a carrier density in the low 1013 cm?2 range, a mobility of 470 cm2/V·s and an effective mass of (0.14 ± 0.03) m0 were extracted. The measurements demonstrate that cavity-enhanced optical Hall effect measurements can be applied to study electronic properties of two-dimensional materials. Paper III. Terahertz cavity-enhanced optical Hall effect measurements are employed to study anisotropic transport in as-grown monolayer, quasi free-standing monolayer and quasi free-standing bilayer epitaxial graphene on semi-insulating 4H-SiC (0001) substrates. The data analysis revealed a strong anisotropy in the carrier mobilities of the quasi freestanding bilayer graphene. The anisotropy is demonstrated to be induced by carriers scattering at the step edges of the SiC, by showing that the mobility is higher along the step than across them. The scattering mechanism is discussed based on the results of the optical Hall effect, low-energy electron microscopy, low-energy electron diffraction and Raman measurements. Paper IV. Mid-infrared spectroscopic ellipsometry and mid-infrared optical Hall effect measurements are employed to determine the electron effective mass in an In0.33Ga0.67N epitaxial layer. The data analysis reveals slightly anisotropic effective mass and carrier mobility parameters together with the optical phonon frequencies and broadenings. Paper V. Terahertz cavity-enhanced optical Hall measurements are employed to study the free charge carrier properties in a set of AlGaN/GaN high electron mobility structures with modified interfaces. The results show that the interface structure has a significant effect on the free charge carrier mobility and that the sample with a sharp interface between an AlGaN barrier and a GaN buffer layers exhibits a record mobility of 2332±73 cm2/V·s. The determined effective mass parameters showed an increase compared to the GaN value, that is attributed the the penetration of the electron wavefunction into the AlGaN barrier layer.
Book Synopsis Study of novel electronic materials by mid-infrared and terahertz optical Hall effect by : Nerijus Armakavicius
Download or read book Study of novel electronic materials by mid-infrared and terahertz optical Hall effect written by Nerijus Armakavicius and published by Linköping University Electronic Press. This book was released on 2017-10-23 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Development of silicon based electronics have revolutionized our every day life during the last three decades. Nowadays Si based devices operate close to their theoretical limits that is becoming a bottleneck for further progress. In particular, for the growing field of high frequency and high power electronics, Si cannot offer the required properties. Development of materials capable of providing high current densities, carrier mobilities and high breakdown fields is crucial for a progress in state of the art electronics. Epitaxial graphene grown on semi-insulating silicon carbide substrates has a high potential to be integrated in the current planar device technologies. High electron mobilities and sheet carrier densities make graphene extremely attractive for high frequency analog applications. One of the remaining challenges is the interaction of epitaxial graphene with the substrate. Typically, much lower free charge carrier mobilities, compared to free standing graphene, and doping, due to charge transfer from the substrate, is reported. Thus, a good understanding of the intrinsic free charge carriers properties and the factors affecting them is very important for further development of epitaxial graphene. III-group nitrides have been extensively studied and already have proven their high efficiency as light sources for short wavelengths. High carrier mobilities and breakdown electric fields were demonstrated for III-group nitrides, making them attractive for high frequency and high power applications. Currently, In-rich InGaN alloys and AlGaN/GaN high electron mobility structures are of high interest for the research community due to open fundamental questions. Electrical characterization techniques, commonly used for the determination of free charge carrier properties, require good ohmic and Schottky contacts, which in certain cases can be difficult to achieve. Access to electrical properties of buried conductive channels in multilayered structures requires modification of samples and good knowledge of the electrical properties of all electrical contact within the structure. Moreover, the use of electrical contacts to electrically characterize two-dimensional electronic materials, such as graphene, can alter their intrinsic properties. Furthermore, the determination of effective mass parameters commonly employs cyclotron resonance and Shubnikov-de Haas oscillations measurements, which require long scattering times of free charge carriers, high magnetic fields and low temperatures. The optical Hall effect is an external magnetic field induced optical anisotropy in conductive layers due to the motion of the free charge carriers under the influence of the Lorentz force, and is equivalent to the electrical Hall effect at optical frequencies. The optical Hall effect can be measured by generalized ellipsometry and provides a powerful method for the determination of free charge carrier properties in a non-destructive and contactless manner. In principle, a single optical Hall effect measurement can provide quantitative information about free charge carrier types, concentrations, mobilities and effective mass parameters at temperatures ranging from few kelvins to room temperature and above. Further, it was demonstrated that for transparent samples, a backside cavity can be employed to enhance the optical Hall effect. Measurement of the optical Hall effect by generalized ellipsometry is an indirect technique requiring subsequent data analysis. Parameterized optical models are fitted to match experimentally measured ellipsometric data by varying physically significant parameters. Analysis of the optical response of samples, containing free charge carriers, employing optical models based on the classical Drude model, which is augmented with an external magnetic field contribution, provide access to the free charge carrier properties. The main research results of the graduate studies presented in this licentiate thesis are summarized in the five scientific papers. Paper I. Description of the custom-built terahertz frequency-domain spectroscopic ellipsometer at Linköping University. The terahertz ellipsometer capabilities are demonstrated by an accurate determination of the isotropic and anisotropic refractive indices of silicon and m-plane sapphire, respectively. Further, terahertz optical Hall effect measurements of an AlGaN/GaN high electron mobility structures were employed to extract the two-dimensional electron gas sheet density, mobility and effective mass parameters. Last, in-situ optical Hall effect measurement on epitaxial graphene in a gas cell with controllable environment, were used to study the effects of environmental doping on the mobility and carrier concentration. Paper II. Presents terahertz cavity-enhanced optical Hall measurements of the monolayer and multilayer epitaxial graphene on semi-insulating 4H-SiC (0001) substrates. The data analysis revealed p-type doping for monolayer graphene with a carrier density in the low 1012 cm?2 range and a carrier mobility of 1550 cm2/V·s. For the multilayer epitaxial graphene, n-type doping with a carrier density in the low 1013 cm?2 range, a mobility of 470 cm2/V·s and an effective mass of (0.14 ± 0.03) m0 were extracted. The measurements demonstrate that cavity-enhanced optical Hall effect measurements can be applied to study electronic properties of two-dimensional materials. Paper III. Terahertz cavity-enhanced optical Hall effect measurements are employed to study anisotropic transport in as-grown monolayer, quasi free-standing monolayer and quasi free-standing bilayer epitaxial graphene on semi-insulating 4H-SiC (0001) substrates. The data analysis revealed a strong anisotropy in the carrier mobilities of the quasi freestanding bilayer graphene. The anisotropy is demonstrated to be induced by carriers scattering at the step edges of the SiC, by showing that the mobility is higher along the step than across them. The scattering mechanism is discussed based on the results of the optical Hall effect, low-energy electron microscopy, low-energy electron diffraction and Raman measurements. Paper IV. Mid-infrared spectroscopic ellipsometry and mid-infrared optical Hall effect measurements are employed to determine the electron effective mass in an In0.33Ga0.67N epitaxial layer. The data analysis reveals slightly anisotropic effective mass and carrier mobility parameters together with the optical phonon frequencies and broadenings. Paper V. Terahertz cavity-enhanced optical Hall measurements are employed to study the free charge carrier properties in a set of AlGaN/GaN high electron mobility structures with modified interfaces. The results show that the interface structure has a significant effect on the free charge carrier mobility and that the sample with a sharp interface between an AlGaN barrier and a GaN buffer layers exhibits a record mobility of 2332±73 cm2/V·s. The determined effective mass parameters showed an increase compared to the GaN value, that is attributed the the penetration of the electron wavefunction into the AlGaN barrier layer.
This volume presents an in-depth review of experimental and theoretical studies on the newly discovered Fe-based superconductors. Following the Introduction, which places iron-based superconductors in the context of other unconventional superconductors, the book is divided into three sections covering sample growth, experimental characterization, and theoretical understanding. To understand the complex structure-property relationships of these materials, results from a wide range of experimental techniques and theoretical approaches are described that probe the electronic and magnetic properties and offer insight into either itinerant or localized electronic states. The extensive reference lists provide a bridge to further reading. Iron-Based Superconductivity is essential reading for advanced undergraduate and graduate students as well as researchers active in the fields of condensed matter physics and materials science in general, particularly those with an interest in correlated metals, frustrated spin systems, superconductivity, and competing orders.
Book Synopsis Iron-Based Superconductivity by : Peter D. Johnson
Download or read book Iron-Based Superconductivity written by Peter D. Johnson and published by Springer. This book was released on 2016-09-24 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents an in-depth review of experimental and theoretical studies on the newly discovered Fe-based superconductors. Following the Introduction, which places iron-based superconductors in the context of other unconventional superconductors, the book is divided into three sections covering sample growth, experimental characterization, and theoretical understanding. To understand the complex structure-property relationships of these materials, results from a wide range of experimental techniques and theoretical approaches are described that probe the electronic and magnetic properties and offer insight into either itinerant or localized electronic states. The extensive reference lists provide a bridge to further reading. Iron-Based Superconductivity is essential reading for advanced undergraduate and graduate students as well as researchers active in the fields of condensed matter physics and materials science in general, particularly those with an interest in correlated metals, frustrated spin systems, superconductivity, and competing orders.
Book Synopsis Superconductivity in Ternary Compounds II by : Merrill B. Maple
Download or read book Superconductivity in Ternary Compounds II written by Merrill B. Maple and published by Springer. This book was released on 2013-11-11 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Books are seldom finished. At best, they are abandoned. The second edition of "Electronic Properties of Materials" has been in use now for about seven years. During this time my publisher gave me ample opportunities to update and improve the text whenever the Ibook was reprinted. There were about six of these reprinting cycles. Eventually, however, it became clear that substantially more new material had to be added to account for the stormy developments which occurred in the field of electrical, optical, and magnetic materials. In particular, expanded sections on flat-panel displays (liquid crystals, electroluminescence devices, field emission displays, and plasma dis. : plays) were added. Further, the recent developments in blue- and green emitting LED's and in photonics are included. Magnetic storage devices also underwent rapid development. Thus, magneto-optical memories, magneto resistance devices, and new' magnetic materials needed to be covered. The sections on dielectric properties, ferroelectricity, piezoelectricity, electrostric tion, and thermoelectric properties have been expanded. Of course, the entire text was critically reviewed, updated, and improved. However, the most extensive change I undertook was the conversion of all equations to SI units throughout. In most of the world and in virtually all of the interna tional scientific journals use of this system of units is required. If today's students do not learn to utilize it, another generation is "lost" on this matter. In other words, it is important that students become comfortable with SI units.
Book Synopsis Electronic Properties of Materials by : Rolf E. Hummel
Download or read book Electronic Properties of Materials written by Rolf E. Hummel and published by Springer. This book was released on 2012-12-06 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: Books are seldom finished. At best, they are abandoned. The second edition of "Electronic Properties of Materials" has been in use now for about seven years. During this time my publisher gave me ample opportunities to update and improve the text whenever the Ibook was reprinted. There were about six of these reprinting cycles. Eventually, however, it became clear that substantially more new material had to be added to account for the stormy developments which occurred in the field of electrical, optical, and magnetic materials. In particular, expanded sections on flat-panel displays (liquid crystals, electroluminescence devices, field emission displays, and plasma dis. : plays) were added. Further, the recent developments in blue- and green emitting LED's and in photonics are included. Magnetic storage devices also underwent rapid development. Thus, magneto-optical memories, magneto resistance devices, and new' magnetic materials needed to be covered. The sections on dielectric properties, ferroelectricity, piezoelectricity, electrostric tion, and thermoelectric properties have been expanded. Of course, the entire text was critically reviewed, updated, and improved. However, the most extensive change I undertook was the conversion of all equations to SI units throughout. In most of the world and in virtually all of the interna tional scientific journals use of this system of units is required. If today's students do not learn to utilize it, another generation is "lost" on this matter. In other words, it is important that students become comfortable with SI units.
The authors of this book present a thorough discussion of the optical properties of solids, with a focus on electron states and their response to electrodynamic fields. A review of the fundamental aspects of the propagation of electromagnetic fields, and their interaction with condensed matter, is given. This is followed by a discussion of the optical properties of metals, semiconductors, and collective states of solids such as superconductors. Theoretical concepts, measurement techniques and experimental results are covered in three interrelated sections. Well-established, mature fields are discussed (for example, classical metals and semiconductors) together with modern topics at the focus of current interest. The substantial reference list included will also prove to be a valuable resource for those interested in the electronic properties of solids. The book is intended for use by advanced undergraduate and graduate students, and researchers active in the fields of condensed matter physics, materials science and optical engineering.
Book Synopsis Electrodynamics of Solids by : Martin Dressel
Download or read book Electrodynamics of Solids written by Martin Dressel and published by Cambridge University Press. This book was released on 2002-01-17 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors of this book present a thorough discussion of the optical properties of solids, with a focus on electron states and their response to electrodynamic fields. A review of the fundamental aspects of the propagation of electromagnetic fields, and their interaction with condensed matter, is given. This is followed by a discussion of the optical properties of metals, semiconductors, and collective states of solids such as superconductors. Theoretical concepts, measurement techniques and experimental results are covered in three interrelated sections. Well-established, mature fields are discussed (for example, classical metals and semiconductors) together with modern topics at the focus of current interest. The substantial reference list included will also prove to be a valuable resource for those interested in the electronic properties of solids. The book is intended for use by advanced undergraduate and graduate students, and researchers active in the fields of condensed matter physics, materials science and optical engineering.
Unconventional superconductivity (or superconductivity with a nontrivial Cooper pairing) is believed to exist in many heavy-fermion materials as well as in high temperature superconductors, and is a subject of great theoretical and experimental interest. The remarkable progress achieved in this field has not been reflected in published monographs and textbooks, and there is a gap between current research and the standard education of solid state physicists in the theory of superconductivity. This book is intended to meet this information need and includes the authors' original results.
Book Synopsis Introduction to Unconventional Superconductivity by : V.P. Mineev
Download or read book Introduction to Unconventional Superconductivity written by V.P. Mineev and published by CRC Press. This book was released on 1999-09-21 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unconventional superconductivity (or superconductivity with a nontrivial Cooper pairing) is believed to exist in many heavy-fermion materials as well as in high temperature superconductors, and is a subject of great theoretical and experimental interest. The remarkable progress achieved in this field has not been reflected in published monographs and textbooks, and there is a gap between current research and the standard education of solid state physicists in the theory of superconductivity. This book is intended to meet this information need and includes the authors' original results.
Book Synopsis Diluted Magnetic (semimagnetic) Semiconductors by : Roshan Lal Aggarwal
Download or read book Diluted Magnetic (semimagnetic) Semiconductors written by Roshan Lal Aggarwal and published by . This book was released on 1987 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:
