Formation of short-range magnetic order and avoided ferromagnetic quantum criticality in pressurized LaCrGe3

LaCrGe3 has attracted attention as a paradigm example of the avoidance of ferromagnetic (FM) quantum criticality in an itinerant magnet. Here, we combined thermodynamic (specific heat and thermal expansion), transport, x-ray, and neutron scattering as well as mu SR measurements to obtain insights on the temperature-pressure phase diagram of LaCrGe3. Consistent with previous studies of the phase diagram by transport measurements, our thermodynamic data shows clearly that the FM transition at T-FM changes its character from second order to first order when it is suppressed to low temperatures by pressure. In addition, previous studies demonstrated that for high pressures a new phase occurs below T-2, which was proposed to be a long-wavelength antiferromagnetic state (AFM(q)). In this paper, we provide evidence from our thermodynamic data that this phase transition is preceded by yet another phase transition at T-1 > T-2. Our mu,SR data indicate that full magnetic volume fraction is only established below T-2, but that this magnetism is characterized by a short correlation length. Within the experimental resolution, our neutron-scattering data is not able to identify any magnetic Bragg peaks. Overall, the microscopic magnetic data is therefore consistent with the formation of FM clusters in the proximity of the avoided FM quantum critical point in LaCrGe3. This conclusion is at odds with the previous proposal of AFM(q) order and raises questions on the role of disorder in this stochiometric compound.

Automated summary

Through various experimental techniques, we have observed changes in the properties of ferromagnetic phase transitions under pressure suppression and the emergence of magnetic phases at high pressures in LaCrGe3. Additionally, evidence suggests a complex relationship between these phase transitions.