Suppression of ferromagnetism governed by a critical lattice parameter in CeTiGe3 with hydrostatic pressure or V substitution

We combine structural and magnetic measurements to compare the different magnetic phase diagrams between the pressure and substitution studies in CeTiGe3. We report on the structural, magnetic, and electrical transport properties of single crystals of CeTi1-xVxGe3 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.9, and 1), and of polycrystalline samples (x = 0.5, 0.6, 0.7, 0.8), as well as structural properties of CeTiGe3 under pressure up to 9GPa. The ferromagnetic ordering in CeTiGe3 is suppressed with V doping in CeTi1-xVxGe3, and suggests a possible ferromagnetic quantum critical point near x = 0.45. We perform a detailed crystalline electric field (CEF) analysis, and the magnetic susceptibility data in pure CeTiGe3 and CeVGe3 can be well explained by the CEF model. The proposed CEF energy levels suggest that there is a gradual change of the ground state from |+/- 5/2 > in CeTiGe3 to |+/- 1/2 > in CeVGe3, and a suppression of CEF splitting energies near the quantum critical region. When hydrostatic pressure is used instead of chemical substitution, the quantum critical point is avoided by the appearance of magnetic phases above around 4.1GPa. In the substitution study, the ferromagnetic and antiferromagnetic regions are well separated, whereas they touch in the pressure study. We observe a different trend in the temperature dependence of the resistivity maximum in both studies, suggesting that the CEF splitting energy is suppressed by V substitution but enhanced by pressure. We also observe different responses in lattice constants between the two studies, highlighting the fact that substitution effects cannot be reduced to chemical pressure effects only. Nevertheless, when the magnetic phase diagrams of both hydrostatic pressure and substitution are compared, we find a common critical lattice constant c = 5.78 angstrom where the ferromagnetic ordering is suppressed in both studies.

Automated summary

We compare the magnetic phase diagrams of CeTiGe3 under pressure and substitution by combining structural and magnetic measurements. The introduction of V doping in CeTi1-xVxGe3 suppresses the ferromagnetic ordering in CeTiGe3, suggesting a possible ferromagnetic quantum critical point near x = 0.45. Detailed crystalline electric field (CEF) analysis reveals a gradual change in the ground state from |+/- 5/2 > in CeTiGe3 to |+/- 1/2 > in CeVGe3, with a suppression of CEF splitting energies near the quantum critical region. The hydrostatic pressure study shows the appearance of magnetic phases above around 4.1GPa, avoiding the quantum critical point, while the substitution study separates the ferromagnetic and antiferromagnetic regions.