Low-energy Excitations In Disordered Solids: A Story Of The 'Universal' Phenomena Of Structural Tunneling

Low-energy excitations in disordered solids have evolved since two-level-tunneling systems were proposed 50 years ago. This book provides a unified, comprehensive description of tunneling systems suitable for graduate students/researchers, focusing on the intrinsic tunneling systems in glassy solids. It describes experimental observations, develops the basic empirical tunneling model, discusses dynamics changes on cooling and heating, and discusses how theories of glass formation can help us understand the ubiquity of these excitations.

Format: Hardback
Length: 420 pages
Publication date: 10 May 2021
Publisher: World Scientific Publishing Co Pte Ltd

Since the initial proposal of two-level-tunneling systems approximately 50 years ago, the field of low-energy excitations has undergone significant evolution. Initially, these systems were employed to explain the common anomalous properties observed in oxide glasses and polymers. However, the scope of this subject has expanded significantly to encompass a wide range of other materials characterized by disorder. This includes amorphous semiconductors, metals, doped-mixed-and quasi-crystals, surface adsorbates, and various other materials. Moreover, the realm of low-energy excitations now encompasses topics such as dephasing of quantum states and interferometer noise.

While a relatively simple empirical description using a limited set of parameters can effectively capture the essence of these excitations, the underlying structures responsible for these effects remain largely unknown in most materials. Furthermore, the reasons for the similarities observed across disparate materials in terms of these excitations have only been qualitatively addressed. To address these gaps, this book offers a comprehensive and unified treatment of tunneling systems in disordered solids, specifically focusing on glassy solids. It provides an introduction to the field for graduate students and researchers seeking to gain a deeper understanding of this area.

The book begins by describing the experimental observations of glassy properties, which serve as the foundation for the subsequent discussions. It then develops the basic empirical tunneling model, which serves as a framework for understanding the behavior of these excitations. The model is carefully worked out in considerable detail, providing a solid foundation for further exploration.

As the book progresses, it delves into the dynamics changes that occur upon cooling to temperatures where direct excitation interactions become significant, as well as upon heating to where tunneling gives way to thermal activation. This comprehensive treatment allows readers to gain insights into the complex behavior of these excitations in various materials.

Furthermore, the book discusses how theories of glass formation can help us understand the ubiquity of these excitations. By examining the structural and compositional aspects of glasses, researchers can gain a deeper understanding of the factors that contribute to the formation of these excitations and their potential applications in various fields.

In conclusion, the development of the basic tunneling model is the core of this book, and it is meticulously worked out in considerable detail. While the scope of the related experimental and theoretical developments is only sketched out here, the text is extensively cited to allow readers to pursue their specific interests in greater depth. This book serves as a valuable resource for graduate students and researchers interested in the field of low-energy excitations in disordered solids, particularly glassy solids.

ISBN-13: 9789811217241