List of symbols and abbreviations ............................. iii
Introduction .................................................... 1
1 Theoretical concepts ......................................... 5
1.1 Introduction to heavy-fermion systems ................... 5
1.1.1 The Kondo effect ................................. 5
1.1.2 Kondo lattice and magnetism in heavy-fermion
systems .......................................... 8
1.1.3 Heavy-fermion and intermediate-valence
systems ......................................... 10
1.2 Superconductivity in heavy-fermion systems ............. 11
1.2.1 Conventional versus unconventional
superconductivity ............................... 11
1.2.2 Unconventional superconductivity mediated by
electrons in heavy-fermion systems .............. 16
a. Magnetically mediated superconductivity ...... 17
b. Valence-fluctuation mediated
superconductivity ............................ 18
1.3 Non-Fermi-liquid behavior in heavy-fermion systems ..... 20
1.3.1 The Landau-Fermi-liquid state ................... 20
1.3.2 Non-Fermi-liquid behavior ....................... 22
1.3.3 Quantum critical phenomena ...................... 22
2 Experimental methods ........................................ 25
2.1 General concepts about heat capacity ................... 25
2.2 The quasiadiabatic heat-pulse technique used for
measurements of heat capacity under high pressure and
at low temperatures .................................... 26
2.2.1 Compensated quasiadiabatic heat-pulse
technique ....................................... 27
2.2.2 High pressure ................................... 29
2.3 Measurements under hydrostatic pressure and data
analysis ............................................... 32
2.3.1 Experimental setup .............................. 32
2.3.2 Measurement techniques .......................... 33
2.4 Measurements in a Quantum Design PPMS .................. 41
3 CenTmIn3n+2m (T: Co, Rh, Ir) family of heavy-fermion
systems ..................................................... 43
3.1 Introduction ........................................... 43
CeCoIn5 ................................................ 46
3.2 Effect of pressure on the heavy-fermion
superconductor CeCoIn5 ................................. 46
3.2.1 Physical properties of CeCoIn5 .................. 46
3.2.2 Experimental results - CeCoIn5 .................. 52
3.2.3 Discussion - CeCoIn5 ............................ 73
Ce2RhIn8 ............................................... 76
3.3 Effect of pressure on the heavy-fermion
antiferromagnet Ce2RhIn8 ............................... 76
3.3.1 Physical properties of Ce2RhIn8 ................. 76
3.3.2 Experimental results - Ce2RhIn8 ................. 80
3.3.3 Discussion - Ce2RhIn8 ........................... 95
4 The heavy-fermion antiferromagnet and superconductor
CeCu2Si2 .................................................... 97
4.1 Short overview ......................................... 97
4.2 Physical properties .................................... 98
4.3 Experimental results .................................. 109
4.3.1 Interplay of antiferromagnetism and
superconductivity in CeCu2Si2 .................. 111
a. A/S-type CeCu2Si2 at ambient pressure ....... 121
b. A/S-type CeCu2Si2 at low pressures .......... 126
4.3.2 Superconductivity in the high-pressure range ... 142
4.3.3 Comparison of the evolution of the
superconducting properties in the different
pressure regimes ............................... 152
4.4 Discussion ............................................ 178
5 Summary .................................................... 183
Bibliography .................................................. 187
Acknowledgments ............................................... 199
Author's declaration .......................................... 201
Versicherung .................................................. 203
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