Since the discovery of high-temperature superconductivity in cuprates, naturally and artificially layered compounds have attracted great interest to induce fascinating superconductivity with high transition temperature and unconventional pairing mechanisms. Extensive studies have developed this field deeper and wider, resulting in the discovery of a wide variety of novel layered superconductors such as ruthenates, nitride chlorides, LaAlOSubscript 3 3/SrTiOSubscript 3 3 heterostructures, and Fe-based superconductors [ 2– 6]. In this section, I introduce the properties of layered superconductors, especially the cuprate and Fe-based high-temperature superconductors.

lgli/9819973120.pdf

lgrsnf/9819973120.pdf

zlib/no-category/Ryosuke Sei/Two-Dimensional Superconductivity in Rare Earth Oxybismuthides with Unusual Valent Bismuth Square Net_27394449.pdf

Springer Nature, Singapore, 2023

Singapore, Singapore

2024

producers:
iTextSharpTM 5.5.14-SNAPSHOT ©2000-2020 iText Group NV (AGPL-version); modified using iTextSharpTM 5.5.14-SNAPSHOT ©2000-2020 iText Group NV (AGPL-version)

Supervisor’s Foreword 6
Acknowledgements 9
Contents 11
1 General Introduction 14
1.1 Layered Superconductors 14
1.1.1 High-Temperature Superconductors 14
1.1.2 Two-Dimensional Superconductivity 15
1.1.3 Complex Phase Diagram 16
1.1.4 Schemes to Search Novel Layered Superconductors 17
1.1.5 Superconductivity in Strong Spin–Orbit Coupled System 18
1.2 Bi Square Net Compounds 19
1.2.1 Crystal Structure 20
1.2.2 Anisotropic Dirac Fermion in Bi Square Net Compounds 24
1.2.3 Kondo Lattice Behavior in CeMBiSubscript 22 26
1.2.4 Potential for Superconducting Bi Square Net 28
1.2.5 Physical Properties of RSubscript 22OSubscript 22Bi (R: rare earth) 29
1.3 Purpose of This Study 31
References 31
2 Experimental Techniques 34
2.1 Sample Preparation 34
2.1.1 Pulsed Laser Deposition 34
2.1.2 Sputtering 34
2.1.3 Vacuum Sealing 36
2.2 Crystallographic Characterization 37
2.2.1 X-Ray Diffraction 37
2.2.2 Rietveld Refinement 38
2.2.3 Atomic Force Microscope 41
2.3 Composition Analysis 42
2.3.1 X-Ray Photoemission Spectroscopy 42
2.3.2 Electron Probe Microanalyzer 43
2.3.3 Inductively Coupled Plasma Mass Spectrometry 44
2.4 Magnetic Measurements 44
2.5 Electrical Measurements 46
2.5.1 Four-Probe Method 46
2.5.2 Hall Measurement 46
2.5.3 Measurement Configuration 47
2.6 Specific Heat Measurements 48
2.6.1 Thermal Relaxation Method 48
2.6.2 Dilution Refrigerator 49
References 50
3 Development of Solid-Phase Epitaxy Techniques 51
3.1 Introduction 51
3.2 Development of Reductive Solid-Phase Epitaxy 53
3.2.1 Experimental 53
3.2.2 Fabrication Results 54
3.2.3 Reaction Mechanism 55
3.2.4 Drawbacks of Reductive Solid-Phase Epitaxy 57
3.3 Development of Multilayer Solid-Phase Epitaxy 57
3.3.1 Experimental 57
3.3.2 Crystal Structure and Valence State of Bi 58
3.3.3 Electronic Transport Properties 61
3.3.4 Onset of Superconductivity 64
3.4 Conclusion 64
References 65
4 Two-Dimensional Superconductivity in Polycrystalline Y2O2Bi 67
4.1 Introduction 67
4.2 Experimental 69
4.3 Crystal Structure 70
4.4 Emergence of Bulk Superconductivity 73
4.4.1 Magnetic Properties 73
4.4.2 Electrical Transport Properties and Two-Dimensional Superconductivity 74
4.4.3 Specific Heat Measurement 76
4.5 Mechanism of Superconductivity 79
4.6 Possible Homologous Series upper Y Subscript n Baseline upper O Subscript n Baseline upper F Subscript n minus 2 Baseline BiYnOnFn-2Bi with Higher Tc 81
4.7 Conclusion 82
References 82
5 Unusual Superconductivity in Tb Subscript 2 Baseline upper O Subscript 2 Baseline BiTb2O2Bi 84
5.1 Introduction 84
5.2 Properties of Pristine Tb2O2Bi 84
5.2.1 Experimental 84
5.2.2 Crystal Structure 85
5.2.3 Physical Properties 86
5.3 Structural Control of Tb2O2Bi 89
5.3.1 Experimental 89
5.3.2 Crystal Structure 91
5.3.3 Physical Properties of F Doped Tb2O2Bi 91
5.3.4 Physical Properties of O Incorporated Tb2O2Bi 96
5.3.5 Complex Phase Diagram 98
5.4 Conclusion 99
References 100
6 Universal Superconductivity in italic upper R Subscript 2 Baseline upper O Subscript 2 Baseline BiR2O2Bi 101
6.1 Introduction 101
6.2 Experimental 101
6.3 Results and Discussion 101
6.4 Conclusion 104
References 104
7 General Conclusion 105
Appendix A Post-Growth of Superconducting Y2O2Bi 107
A.1 Introduction 107
A.2 Experimental 107
A.3 Results and Discussion 108
A.4 Conclusion 110
Appendix B Synthesis of Polycrystalline Dy2O2Bi 111
B.1 Introduction 111
B.2 Experimental 111
B.3 Results and Discussion for Pristine Dy2O2Bi 112
B.4 Results and Discussion for F doped Dy2O2Bi 114
B.5 Results and Discussion for O Incorporated Dy2O2Bi 116
B.6 Conclusion 116
Appendix C Synthesis of Polycrystalline Lu2O2Bi 118
C.1 Introduction 118
C.2 Experimental 118
C.3 Results and Discussion 118
C.4 Conclusion 120
Appendix D Fabrication of Dy2O2Bi Thin Film 121
D.1 Experimental 121
D.2 Crystal Structure 121
D.3 Physical Properties 122
D.4 Conclusion 124

This book elucidates fascinating electronic phenomena of unusual Bi2-square net in layered R2O2Bi (R: rare earth) compounds using two approaches: the fabrication of epitaxial thin films and the synthesis of bulk polycrystalline powders. The Bi2-square net compounds are a promising platform to explore exotic physical properties originating from the interplay between a two-dimensional electronic state and strong spin–orbit coupling; however, there are few reports on Bi2-square net compounds due to the instability of unusual electronic configurations. The book presents the development of synthetic routes for R2O2Bi compounds, such as novel solid phase epitaxy techniques and chemical control of crystal structure, demonstrating the intrinsic physical properties of Bi2-square net for the first time. The most notable finding is the successful induction of two-dimensional superconductivity in Bi2-square net with the coexistence of rich electronic phases. The book also discusses the superconducting mechanisms and the effect of R cation substitution in detail and describes the mechanical properties of Bi2-square net. These findings overturn the results of previous studies of R2O2Bi. The book sheds light on hidden layered compounds, representing a significant advance in the field.

2023-12-28