Microscopic Magnetic Characterization of Quantum Criticality in LaCrGe₃ using ¹³⁹La NMR under Pressure

LaCrGe₃ is a peculiar itinerant ferromagnet with a unique route to avoid a ferromagnetic quantum critical point (QCP) by not only changing the order of the phase transition from second to first, but also through the appearance of a high-pressure magnetic phase. Expanding on earlier work which suggested that the high-pressure magnetic phase could be a short-range magnetically ordered cluster phase, ¹³⁹La nuclear magnetic resonance (NMR) measurements were carried out under pressure up to 2.64 GPa. The NMR spectrum measurements suggest that a ferromagnetic order develops below 50 K at pressures higher than ~1.5 GPa under the applied magnetic field of 7.2 T. Furthermore, three-dimensional ferromagnetic fluctuations were found in the paramagnetic state which persisted even at high pressures close to the putative QCP. These findings provide a novel insight into the quantum criticality of this system.