Observation of Superconductivity in Epitaxially Grown Atomic Layers (eBook)

Satoru Ichinokura, a post-doctoral researcher of the Japan Society for the Promotion of Science (JSPS) at The University of Tokyo, is an experimentalist in surface physics and nanotechnology. His work is concerned with atomic-scale thin layer systems such as graphene, transition metal dichalcogenides, and metal-induced surface reconstructions on semiconductors. He is interested particularly in spintronics aspects and low-temperature properties of those materials, represented by superconductivity, and approaches them by electric transport measurements and scanning tunneling microscopy. Satoru Ichinokura received both his Bachelor of Physics and Master of Science in physics from Tohoku University in 2011 and 2013, respectively. Thereafter he joined the group led by Professor Shuji Hasegawa in the Department of Physics, The University of Tokyo, and received his Ph.D. in physics from The University of Tokyo in 2016. During his Master’s program, he received a research grant of Global Centers of Excellence Program from Tohoku University in 2012. During his doctoral program, he received a travel award and student award from the Surface Science Society and a Graduate School of Science award from the School of Science, The University of Tokyo, in 2014, 2015, and 2016, respectively. He was also awarded a research fellowship for young scientists from JSPS, and his research was supported by the JSPS between April 2015 and March 2017.

Supervisor’s Foreword 7
Preface 9
List of Published Articles 11
Acknowledgements 12
Contents 14
Abbreviations and Constants 17
1 Introduction 19
1.1 Historical Background 19
1.1.1 Two-Dimensional Electron Systems 19
1.1.2 Surface Superstructures 20
1.1.3 Superconductivity 22
1.1.4 Two-Dimensional Superconductivity 23
1.1.5 Superconductivity in Surface States 25
1.1.6 Atomic Thick Superconductors 27
1.2 Direction of This Study 29
1.3 Structure of This Thesis 30
References 30
2 Fundamentals 33
2.1 Surface Electronic States and Spatial Inversion Symmetry 33
2.1.1 Rashba Effect 34
2.2 Electrical Transport 36
2.2.1 Drude Model 36
2.2.2 Boltzmann Equation 36
2.2.3 Matthiessen's Low 38
2.2.4 Loffe-Regel Limit 39
2.3 Basic Properties of Superconductivity 39
2.3.1 London Equation 40
2.3.2 GL Theory 42
2.3.3 BCS Theory 48
2.3.4 Josephson Effect and Critical Current 58
2.4 Special Cases of Superconductivity 59
2.4.1 Strong Coupled Superconductor 59
2.4.2 Two-Dimensional Superconductivity 61
2.4.3 Disorder-Induced Superconductor-Insulator Transition 64
2.4.4 Superconductivity Without Spatial Inversion Symmetry 65
References 68
3 Experimental Methods 70
3.1 Electron Diffraction 70
3.2 Electrical Transport Measurement 73
3.3 Experimental Apparatus 76
References 78
4 Thallium Biatomic Layer 80
4.1 Background 80
4.2 Structural Properties of Si(111)-6times6-Tl 81
4.2.1 Atomic Arrangement 81
4.2.2 Electronic Structure 82
4.3 Purpose of This Study 84
4.4 Electrical Transport Studies on Si(111)-6times6-Tl 85
4.4.1 Sample Preparation 85
4.4.2 Results 86
4.4.3 Discussion 91
4.5 Summary 93
References 93
5 Thallium-Lead Monatomic-layer Compound 95
5.1 Background 95
5.2 Structural Properties of Si(111) -sqrt3timessqrt3-(Tl, Pb) 96
5.2.1 Atomic Arrangement 96
5.2.2 Electronic Structure 96
5.3 Purpose of This Study 99
5.4 Electrical Transport Studies on Si(111)-sqrt3timessqrt3- (Tl, Pb) 100
5.4.1 Sample Preparation 100
5.4.2 Results 101
5.4.3 Discussion 105
5.5 Summary 106
References 106
6 Intercalation Compounds of Bilayer Graphene 108
6.1 Background 108
6.1.1 Graphaite Intercalation Compounds 109
6.1.2 Metal Doping to Graphene 111
6.2 Structural Properties of Intercalation Compounds of Bilayer Graphene 113
6.2.1 Graphene on SiC 113
6.2.2 Atomic Arrangement 113
6.2.3 Electronic Structure 117
6.3 Purpose of This Study 119
6.4 Electrical Transport Studies on Intercalation Compounds of Bilayer Graphene 119
6.4.1 Sample Preparation 119
6.4.2 Results on Pristine Bilayer Graphene 121
6.4.3 Results on C6LiC6 and C6CaC6 122
6.4.4 Discussion 125
6.5 Summary 127
References 127
7 Conclusion 129
7.1 General Statement 129
7.1.1 Electronic Structure and Superconductivity 129
7.1.2 Two-Dimensionality 130
7.2 Outlook 131
References 132
Appendix Curriculum Vitae 134