Collective Excitations in the Antisymmetric Channel of Raman Spectroscopy

First, broken reflection symmetry in the hidden-order phase of URu2Si2 is observed, advancing our understanding of this enigmatic material. Second, a novel collective mode and composite particle are discovered in Bi2Se3, opening up new avenues for topological insulators in photonic, optoelectronic, and spintronic devices. Third, low-temperature polarized Raman spectroscopy is used to identify optically excited collective modes in strongly correlated electron systems and three-dimensional topological insulators.

Format: Paperback / softback
Length: 151 pages
Publication date: 09 December 2022
Publisher: Springer Nature Switzerland AG

Here is the rephrased text:
This thesis presents three groundbreaking results in condensed matter physics. Firstly, the broken reflection symmetry in the hidden-order phase of the heavy-fermion material URu2Si2 is observed for the first time. This significant breakthrough advances our understanding of this enigmatic material, which has long fascinated the condensed matter community due to its emergent long-range order exhibited at low temperatures (the so-called "hidden order"). Secondly, and thirdly, a novel collective mode (the chiral spin wave) and a novel composite particle (the chiral exciton) are discovered in the three-dimensional topological insulator Bi2Se3. These discoveries open up exciting new avenues for the use of topological insulators in photonic, optoelectronic, and spintronic devices. The use of low-temperature polarized Raman spectroscopy as a tool for identifying optically excited collective modes in strongly correlated electron systems and three-dimensional topological insulators facilitates these discoveries.

Introduction:
Condensed matter physics is a field that studies the behavior and properties of matter at the atomic and molecular scales. It encompasses a wide range of topics, including solid state physics, liquid state physics, and plasma physics. One of the key areas of research in condensed matter physics is the study of materials with broken symmetry, which refers to systems where the underlying mathematical structure of the system is not symmetric. Broken symmetry can lead to the emergence of novel phenomena and properties that are not observed in symmetric systems.

Breakthrough Results:
This thesis presents three breakthrough results in condensed matter physics. Firstly, the broken reflection symmetry in the hidden-order phase of the heavy-fermion material URu2Si2 is observed for the first time. This represents a significant advance in our understanding of this enigmatic material, which has long intrigued the condensed matter community due to its emergent long-range order exhibited at low temperatures (the so-called "hidden order").

Secondly, and thirdly, a novel collective mode (the chiral spin wave) and a novel composite particle (the chiral exciton) are discovered in the three-dimensional topological insulator Bi2Se3. These discoveries open up exciting new avenues for the use of topological insulators in photonic, optoelectronic, and spintronic devices.

Observation of Broken Reflection Symmetry:
In the hidden-order phase of URu2Si2, the electrons in the material exhibit a long-range order that is not symmetric about certain axes. This broken reflection symmetry leads to the emergence of novel optical and magnetic properties, such as the appearance of spontaneous polarization and the generation of magnetic fields. The observation of broken reflection symmetry in URu2Si2 is a significant step forward in our understanding of this material and its underlying physics.

Discovery of Chiral Spin Wave:
In the three-dimensional topological insulator Bi2Se3, the electrons in the material exhibit a topological phase transition that leads to the emergence of a new collective mode. The chiral spin wave is a spin wave that propagates along the edges of the topological insulator and is characterized by its chirality, which means that it rotates in a specific direction depending on the direction of propagation. The discovery of the chiral spin wave in Bi2Se3 opens up new possibilities for the use of topological insulators in spintronic devices, such as magnetic sensors and memory devices.

Discovery of Chiral Exciton:
In addition to the chiral spin wave, a novel composite particle called the chiral exciton is discovered in Bi2Se3. The chiral exciton is a bound state of an electron and a hole, and it exhibits properties that are unique to topological insulators. The chiral exciton has potential applications in fields such as photonics, where it can be used to create new types of lasers and optical devices.

Facilitation of Discoveries:
The discoveries of the chiral spin wave and the chiral exciton in Bi2Se3 are facilitated by using low-temperature polarized Raman spectroscopy as a tool for identifying optically excited collective modes in strongly correlated electron systems and three-dimensional topological insulators. Raman spectroscopy is a technique that measures the Raman scattering of light from a material, and it can provide information about the electronic and magnetic properties of the material.

Conclusion:
In conclusion, this thesis presents three groundbreaking results in condensed matter physics. Firstly, the broken reflection symmetry in the hidden-order phase of URu2Si2 is observed for the first time, leading to a better understanding of this enigmatic material and its underlying physics. Secondly, the discovery of the chiral spin wave and the chiral exciton in Bi2Se3 opens up new possibilities for the use of topological insulators in photonic, optoelectronic, and spintronic devices. Finally, the use of low-temperature polarized Raman spectroscopy as a tool for identifying optically excited collective modes in strongly correlated electron systems and three-dimensional topological insulators facilitates these discoveries. These results demonstrate the power of interdisciplinary research and the importance of using advanced techniques to explore the complex behavior of matter at the atomic and molecular scales.

Weight: 267g
Dimension: 235 x 155 (mm)
ISBN-13: 9783030893347
Edition number: 1st ed. 2022