Magnetothermal Properties near Quantum Criticality in the Itinerant Metamagnet Sr3Ru2O7 (eBook)

Supervisor’s Foreword 6
Acknowledgments 8
Contents 10
Introduction 12
References 15
Background Physics 17
2.1 Itinerant Electron Systems 17
2.1.1 Non-Interacting Electron Theory 18
2.1.2 Magnetic Field Effects 22
2.1.3 Electric Transport 27
2.1.4 The Fermi Liquid 28
2.1.5 Beyond the Fermi Liquid 30
2.2 The Physics of the Ruthenate Family 34
2.2.1 Crystal Structure and Synthesis 34
2.2.2 Thermodynamic Properties and Magnetic Phase Diagram 35
2.2.3 Electronic Structure Properties 44
2.3 Summary 51
References 52
Thermodynamic Measurements of Entropy 55
3.1 General Considerations on Thermodynamics in Magnetic Fields 56
3.1.1 The Laws of Thermodynamics for Magnetic Systems 56
3.1.2 Phase Transitions 59
3.2 Experimental Consequences 60
3.2.1 Principle of Specific Heat Measurements 61
3.2.2 Magnetocaloric Measurements 66
References 73
Design and Characterisation of Novel Experimental Setup 75
4.1 Measurement Environment and Sample Holder 75
4.2 Design of Experimental Setup 77
4.2.1 Design Goals and Experimental Realisation 77
4.2.2 Sample Platform and Thermal Bath 78
4.2.3 Thermometer 80
4.2.4 Heater 81
4.2.5 Estimates of Thermal Performance 82
4.3 Thermometry 85
4.3.1 Physical Properties of Thermometers 85
4.3.2 Thermometer Calibration 88
4.4 Characterisation Run With Sr2RuO4 92
4.4.1 Sample 93
4.4.2 Specific Heat in Field 93
4.4.3 Specific Heat at Zero Field 96
4.4.4 Magnetocaloric Oscillations 96
4.5 Characteristics and Details of Measurements on Sr3Ru2O7 98
4.5.1 Sample Selection 98
4.5.2 Thermal Link 99
4.5.3 Specific Heat 100
References 101
Experimental Results and Discussion 103
5.1 Caloric Studies of Magnetic Phase Transitions in Sr3Ru2O7 104
5.1.1 Evolution of Entropy across Phase Transitions as a Function of Field 104
5.1.2 Specific Heat Signature of Phase Transitions 111
5.1.3 Discussion 114
5.2 The Low and High Field States of Sr3Ru2O7 122
5.2.1 The Low Field Fermi Liquid State 122
5.2.2 The High Field Fermi Liquid State 127
5.2.3 Discussion 129
References 139
Conclusions and Future Work 142
References 146
Appendices 148
7.1 Appendix A: Material Properties 148
7.2 Appendix B: Angular Dependence of the Magnetocaloric Signal 148
7.2.1 Study at 19 150
7.2.2 Study in the ab-Plane 151
References 153