Quantum tricritical point in the temperature-pressure-magnetic field phase diagram of CeTiGe3

We report the temperature-pressure-magnetic-field phase diagram of the ferromagnetic Kondo-lattice CeTiGe₃ determined by means of electrical resistivity measurements. Measurements up to ~5.8GPa reveal a rich phase diagram with multiple phase transitions. At ambient pressure, CeTiGe₃ orders ferromagnetically at T_C =14 K. Application of pressure suppresses T_C, but a pressure induced ferromagnetic quantum criticality is avoided by the appearance of two new successive transitions for p>4.1GPa that are probably antiferromagnetic in nature. These two transitions are suppressed under pressure, with the lower temperature phase being fully suppressed above 5.3GPa. The critical pressures for the presumed quantum phase transitions are p1≅4.1GPa and p2≅5.3GPa. Above 4.1GPa, application of magnetic field shows a tricritical point evolving into a wing-structure phase with a quantum tricritical point at 2.8T at 5.4GPa, where the first-order antiferromagnetic-ferromagnetic transition changes into the second order antiferromagnetic-ferromagnetic transition.