Tuning Competing Ground States in LuFe₄Ge₂ Using External Pressure

Exotic phenomena and unconventional phases occur at regions of competing energy scales in correlated materials, especially in systems with magnetic frustration. Here, we investigate LuFe₄Ge₂ under external pressure in order to better understand the interplay between competing ground states. LuFe₄Ge₂ is a frustrated, itinerant magnetic system with antiferromagnetic (AFM) ordering accompanied by a structural transition at 36 K. The pressure dependence of the magneto-elastic transition in LuFe₄Ge₂ has been investigated using electrical transport, ac magnetic susceptibility, X-ray diffraction, Mössbauer, and muon-spin resonance (μSR) measurements under external pressure. External pressure suppresses the first-order magnetic transition (AFM1) at around 1.8 GPa, while the structural transition is largely unaffected by pressure. A new pressure-induced magnetic phase is confirmed by Mössbauer and μSR experiments. Mössbauer investigations indicate that the high pressure phase is also antiferromagnetically ordered (AFM2), with a different size of the ordered moment and/or a different magnetic structure. Further studies to understand the pressure-induced phase and the interplay between magnetic and structural phase transitions are under way.