Quantum phase transitions in geometrically frustrated heavy-fermion compounds

The competition between the Kondo effect and the Ruderman- Kittel- Kasuya-Yosida exchange interaction determines the ground state of most heavy- fermion compounds. By employing non-thermal tuning parameters like pressure and magnetic field, Fermi liquids and magnetically ordered phases can be tuned smoothly to each other in these compounds, offering an ideal playground for quantum criticality. On the other hand, spin frustration is an effective approach to produce novel quantum phenomena such as spin liquids in insulating quantum magnets. Introducing spin frustration into heavy fermion systems will profoundly affect their ground state, and is emerging as a new research direction. Following a brief introduction to frustrated heavy-fermion compounds, we will first describe our recent work on frustrated CePdAl, and then discuss the observed quantumcritical phase that is intimately related to spin frustration.