Quantum tricritical point in the temperature-pressure-magnetic field phase diagram of CeTiGe$_3$

TL;DR

This study maps the complex temperature-pressure-magnetic field phase diagram of CeTiGe$_3$, revealing a quantum tricritical point and multiple phase transitions, including a wing structure phase and suppression of magnetic order under pressure.

Contribution

It provides the first detailed phase diagram of CeTiGe$_3$ under combined pressure and magnetic field, identifying a quantum tricritical point and new antiferromagnetic phases.

Findings

Identification of a quantum tricritical point at 2.8 T and 5.4 GPa.

Observation of pressure-induced suppression of ferromagnetic order.

Discovery of a wing structure phase with multiple phase transitions.

Abstract

We report the temperature-pressure-magnetic field phase diagram of the ferromagnetic Kondo-lattice CeTiGe$_3$ determined by means of electrical resistivity measurements. Measurements up to $\sim$ 5.8 GPa reveal a rich phase diagram with multiple phase transitions. At ambient pressure, CeTiGe$_3$ orders ferromagnetically at $T_\text{C}$ = 14 K. Application of pressure suppresses $T_\text{C}$, but a pressure induced ferromagnetic quantum criticality is avoided by the appearance of two new successive transitions for $p$ $>$ 4.1 GPa that are probably antiferromagnetic in nature. These two transitions are suppressed under pressure, with the lower temperature phase being fully suppressed above 5.3 GPa. The critical pressures for the presumed quantum phase transitions are $p_1$ $\cong$ 4.1 GPa and $p_2$ $\cong$ 5.3 GPa. Above 4.1 GPa, application of magnetic field shows a tricritical point evolving into a wing structure phase with a quantum tricritical point at 2.8 T at 5.4 GPa, where the first order antiferromagnetic-ferromagnetic transition changes into the second order antiferromagnetic-ferromagnetic transition.