Since the initial predictions for the existence of Weyl fermions in condensed matter, many different experimental techniques have confirmed the existence of Weyl semimetals. Among these techniques, optical responses have shown a variety of effects associated with the existence of Weyl fermions. In chiral crystals, we find a new type of fermions protected by crystal symmetries — the chiral multifold fermions — that can be understood as a higher-spin generalization of Weyl fermions. This work provides a complete description of all chiral multifold fermions, studying their topological properties and the k·p models describing them. We compute the optical conductivity of all chiral multifold fermions and establish their optical selection rules. We find that the activation frequencies are different for each type of multifold fermion, thus constituting an experimental fingerprint for each type of multifold fermion. Building on the theoretical results obtained in the first part of our analysis, we study two chiral multifold semimetals: RhSi and CoSi. We analyze the experimental results with k·p and tight-binding models based on the crystal symmetries of the material. We trace back the features observed in the experimental optical conductivity to the existence of multifold fermions near the Fermi level and estimate the chemical potential and the scattering lifetime in both materials. Finally, we provide an overview of second-order optical responses and study the second-harmonic generation of RhSi. We find a sizeable second-harmonic response in the low-energy regime associated with optical transitions between topological bands. However, this regime is extremely challenging to access with the current experimental techniques. We conclude by providing an overview of the main results, highlighting potential avenues to further research on chiral multifold semimetals and the future of optical responses as experimental probes to characterize topological phases.

This book covers basic and advanced aspects in the field of Topological Matter. The chapters are based on the lectures presented during the Topological Matter School 2017. It provides graduate level content introducing the basic concepts of the field, including an introductory session on group theory and topological classification of matter. Different topological phases such as Weyls semi-metals, Majoranas fermions and topological superconductivity are also covered. A review chapter on the major experimental achievements in the field is also provided. The book is suitable not only for master, graduate and young postdoctoral researchers, but also to senior scientists who want to acquaint themselves with the subject.

Modern electronic devices and novel materials often derive their extraordinary properties from the intriguing, complex behavior of large numbers of electrons forming what is known as an electron liquid. This book provides an in-depth introduction to the physics of the interacting electron liquid in a broad variety of systems, including metals, semiconductors, artificial nano-structures, atoms and molecules. One, two and three dimensional systems are treated separately and in parallel. Different phases of the electron liquid, from the Landau Fermi liquid to the Wigner crystal, from the Luttinger liquid to the quantum Hall liquid are extensively discussed. Both static and time-dependent density functional theory are presented in detail. Although the emphasis is on the development of the basic physical ideas and on a critical discussion of the most useful approximations, the formal derivation of the results is highly detailed and based on the simplest, most direct methods.

In a new branch of physics and technology, called spin-electronics or spintronics, the flow of electrical charge (usual current) as well as the flow of electron spin, the so-called "spin current", are manipulated and controlled together. This book is intended to provide an introduction and guide to the new physics and applications of spin current.

Superconductivity in materials without inversion symmetry in the respective crystal structures occurs in the presence of antisymmetric spin-orbit coupling as a consequence of an emerging electric field gradient. The superconducting condensate is then a superposition of spin-singlet and spin-triplet Cooper pairs. This scenario accounts for various experimental findings such as nodes in the superconducting gap or extremely large upper critical magnetic fields. Spin-triplet pairing can occur in non-centrosymmetric superconductors in spite of Anderson’s theorem that spin-triplet pairing requires a crystal structure that exhibits inversion symmetry. This book, authored and edited by leading researchers in the field, is both an introduction to and overview on this exciting branch of novel superconductors. Its self-contained and tutorial style makes it particularly suitable for self-study and as source of teaching material for special seminars and courses. At the same time it constitutes an up-to-date and authoritative reference for anyone working in this exciting field.

The tremendous impact of electronic devices on our lives is the result of continuous improvements of the billions of nanoelectronic components inside integrated circuits (ICs). However, ultra-scaled semiconductor devices require nanometer control of the many parameters essential for their fabrication. Through the years, this created a strong alliance between microscopy techniques and IC manufacturing. This book reviews the latest progress in IC devices, with emphasis on the impact of electrical atomic force microscopy (AFM) techniques for their development. The operation principles of many techniques are introduced, and the associated metrology challenges described. Blending the expertise of industrial specialists and academic researchers, the chapters are dedicated to various AFM methods and their impact on the development of emerging nanoelectronic devices. The goal is to introduce the major electrical AFM methods, following the journey that has seen our lives changed by the advent of ubiquitous nanoelectronics devices, and has extended our capability to sense matter on a scale previously inaccessible.

This book summarizes the basic physics of graphite and newly discovered phenomena in this material. The book contains the knowledge needed to understand novel properties of functionalized graphite demonstrating the occurrence of remarkable phenomena in disordered graphite and graphite-based heterostructures. It also discusses applications of thin graphitic samples in future electronics. Graphite consists of a stack of nearly decoupled two-dimensional graphene planes. Because of the low dimensionality and the presence of Dirac fermions, much of graphite physics resembles that of graphene. On the other hand, the multi-layered nature of the graphite structure together with structural and/or chemical disorder are responsible for phenomena that are not observed yet in graphene, such as ferromagnetic order and superconductivity. Each chapter was written by one or more experts in the field whose contributions were relevant in the (re)discovery of (un)known phenomena in graphite. The book is intended as reference for beginners and experts in the field, introducing them to many aspects of the new physics of graphite, with a fresh overview of recently found phenomena and the theoretical frames to understand them.