Angle-Resolved Photoemission


Book Description

Angle-resolved photoemission has become an indispensable tool for solid state and surface physicists and chemists. This book covers the underlying phenomenology of the technique, reviews its application to existing problems, and discusses future applications. The book is particularly timely given the significant improvements in experimental and theoretical methodology which have recently been or soon will be attained, namely, ultrahigh resolution studies using improved sources of synchrotron radiation, quasiparticle interpretation of measured dispersion relations and spectra, in situ growth of novel materials, etc. The technique has been applied predominantly to understand materials for which the one-electron paradigm is a reasonable approximation. Most chapters discuss this type of experiment: 2D and 3D states in metals and semiconductors, extrinsic states induced by adsorption, etc. Applications of the technique to materials where electron correlation plays a comparable role to that of solid state hybridization, ferro- and antiferromagnets, high Tc superconductors, etc. are rapidly growing in popularity. These areas are also discussed and a foundation is laid for further experiments in this direction. Almost all chapters contain comprehensive bibliographies and compendia of systems studied. The book has an extensive index which cross references applications and systems studied.




Photoemission Spectroscopy on High Temperature Superconductor


Book Description

This book mainly focuses on the study of the high-temperature superconductor Bi2Sr2CaCu2O8 by vacuum, ultra-violet, laser-based, angle-resolved photoemission spectroscopy (ARPES). A new form of electron coupling has been identified in Bi2212, which occurs in the superconducting state. For the first time, the Bogoliubov quasiparticle dispersion with a clear band back-bending has been observed with two peaks in the momentum distribution curve in the superconducting state at a low temperature. Readers will find useful information about the technique of angle-resolved photoemission and the study of high-temperature superconductors using this technique. Dr. Wentao Zhang received his PhD from the Institute of Physics at the Chinese Academy of Sciences.




Photoelectron Spectroscopy


Book Description

Photoelectron spectroscopy is now becoming more and more required to investigate electronic structures of various solid materials in the bulk, on surfaces as well as at buried interfaces. The energy resolution was much improved in the last decade down to 1 meV in the low photon energy region. Now this technique is available from a few eV up to 10 keV by use of lasers, electron cyclotron resonance lamps in addition to synchrotron radiation and X-ray tubes. High resolution angle resolved photoelectron spectroscopy (ARPES) is now widely applied to band mapping of materials. It attracts a wide attention from both fundamental science and material engineering. Studies of the dynamics of excited states are feasible by time of flight spectroscopy with fully utilizing the pulse structures of synchrotron radiation as well as lasers including the free electron lasers (FEL). Spin resolved studies also made dramatic progress by using higher efficiency spin detectors and two dimensional spin detectors. Polarization dependent measurements in the whole photon energy spectrum of the spectra provide useful information on the symmetry of orbitals. The book deals with the fundamental concepts and approaches for the application of this technique to materials studies. Complementary techniques such as inverse photoemission, photoelectron diffraction, photon spectroscopy including infrared and X-ray and scanning tunneling spectroscopy are presented. This book provides not only a wide scope of photoelectron spectroscopy of solids but also extends our understanding of electronic structures beyond photoelectron spectroscopy.




Coherent Light-Matter Interactions in Monolayer Transition-Metal Dichalcogenides


Book Description

This thesis presents optical methods to split the energy levels of electronic valleys in transition-metal dichalcogenides (TMDs) by means of coherent light-matter interactions. The electronic valleys found in monolayer TMDs such as MoS2, WS2, and WSe2 are among the many novel properties exhibited by semiconductors when thinned down to a few atomic layers, and have have been proposed as a new way to carry information in next generation devices (so-called valleytronics). These valleys are, however, normally locked in the same energy level, which limits their potential use for applications. The author describes experiments performed with a pump-probe technique using transient absorption spectroscopy on MoS2 and WS2. It is demonstrated that hybridizing the electronic valleys with light allows one to optically tune their energy levels in a controllable valley-selective manner. In particular, by using off-resonance circularly polarized light at small detuning, one can tune the energy level of one valley through the optical Stark effect. Also presented within are observations, at larger detuning, of a separate contribution from the so-called Bloch--Siegert effect, a delicate phenomenon that has eluded direct observation in solids. The two effects obey opposite selection rules, enabling one to separate the two effects at two different valleys.




Modern Techniques of Surface Science


Book Description

Revised and expanded second edition of the standard work on new techniques for studying solid surfaces.




Angle-Resolved Photoemission Spectroscopy on High-Temperature Superconductors


Book Description

This book mainly focuses on the study of the high-temperature superconductor Bi2Sr2CaCu2O8+δ (Bi2212) and single-layer FeSe film grown on SrTiO3 (STO) substrate by means of angle-resolved photoemission spectroscopy (ARPES). It provides the first electronic evidence for the origin of the anomalous high-temperature superconductivity in single-layer FeSe grown on SrTiO3 substrate. Two coexisted sharp-mode couplings have been identified in superconducting Bi2212. The first ARPES study on single-layer FeSe/STO films has provided key insights into the electronic origin of superconductivity in this system. A phase diagram and electronic indication of high Tc and insulator to superconductor crossover have been established in the single-layer FeSe/STO films. Readers will find essential information on the techniques used and interesting physical phenomena observed by ARPES.




Photoelectron Spectroscopy


Book Description

An up-to-date introduction to the field, treating in depth the electronic structures of atoms, molecules, solids and surfaces, together with brief descriptions of inverse photoemission, spin-polarized photoemission and photoelectron diffraction. Experimental aspects are considered throughout and the results carefully interpreted by theory. A wealth of measured data is presented in tabullar for easy use by experimentalists.




Angle-Resolved Photoemission Spectroscopy Study of Spin Fluctuations in the Cuprate Superconductors


Book Description

This thesis makes significant advances towards an understanding of superconductivity in the cuprate family of unconventional, high-temperature superconductors. Even though the high-temperature superconductors were discovered over 35 years ago, there is not yet a general consensus on an acceptable theory of superconductivity in these materials. One of the early proposals suggested that collective magnetic excitations of the conduction electrons could lead them to form pairs, which in turn condense to form the superconducting state at a critical temperature Tc. Quantitative calculations of Tc using experimental data were, however, not available to verify the applicability of this magnetic mechanism. In this thesis, the author constructed an angle-resolved photoemission apparatus that could provide sufficiently accurate data of the electronic excitation spectra of samples in the normal state, data which was furthermore unusually devoid of any surface contamination. The author also applied the Bethe-Salpeter method to his uncommonly pristine and precise normal state data, and was able to predict the approximate superconducting transition temperatures of different samples. This rare combination of experiment with sophisticated theoretical calculations leads to the conclusion that antiferromagnetic correlations are a viable candidate for the pairing interaction in the cuprate superconductors.




In Situ Characterization of Thin Film Growth


Book Description

Advanced techniques for characterizing thin film growth in situ help to develop improved understanding and faster diagnosis of issues with the process. In situ characterization of thin film growth reviews current and developing techniques for characterizing the growth of thin films, covering an important gap in research.Part one covers electron diffraction techniques for in situ study of thin film growth, including chapters on topics such as reflection high-energy electron diffraction (RHEED) and inelastic scattering techniques. Part two focuses on photoemission techniques, with chapters covering ultraviolet photoemission spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS) and in situ spectroscopic ellipsometry for characterization of thin film growth. Finally, part three discusses alternative in situ characterization techniques. Chapters focus on topics such as ion beam surface characterization, real time in situ surface monitoring of thin film growth, deposition vapour monitoring and the use of surface x-ray diffraction for studying epitaxial film growth.With its distinguished editors and international team of contributors, In situ characterization of thin film growth is a standard reference for materials scientists and engineers in the electronics and photonics industries, as well as all those with an academic research interest in this area. - Chapters review electron diffraction techniques, including the methodology for observations and measurements - Discusses the principles and applications of photoemission techniques - Examines alternative in situ characterisation techniques




Angle-Resolved Photoemission Spectroscopy Studies of 2D Material Heterostructures


Book Description

This book focuses on angle-resolved photoemission spectroscopy studies on novel interfacial phenomena in three typical two-dimensional material heterostructures: graphene/h-BN, twisted bilayer graphene, and topological insulator/high-temperature superconductors. Since the discovery of graphene, two-dimensional materials have proven to be quite a large “family”. As an alternative to searching for other family members with distinct properties, the combination of two-dimensional (2D) materials to construct heterostructures offers a new platform for achieving new quantum phenomena, exploring new physics, and designing new quantum devices. By stacking different 2D materials together and utilizing interfacial periodical potential and order-parameter coupling, the resulting heterostructure’s electronic properties can be tuned to achieve novel properties distinct from those of its constituent materials. This book offers a valuable reference guide for all researchers and students working in the area of condensed matter physics and materials science.