Interplay of structure and magnetism in LuFe4⁢Ge2 tuned by hydrostatic pressure

• Published in: Physical review. B 2023-03, Vol.107 (12)
• Main Authors: Ajeesh, M. O., Materne, P., dos Reis, R. D., Weber, K., Dengre, S., Sarkar, R., Khasanov, R., Kraft, I., León, A. M., Bi, W., Zhao, J., Alp, E. E., Medvedev, S., Ksenofontov, V., Rosner, H., Klauss, H. -H., Geibel, C., Nicklas, M.
• Format: Article
• Language: English
• Subjects: antiferromagnets; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; density functional theory; frustrated magnetism; intermetallic compounds; magnetic phase transitions; magnetism; muon spin relaxation; muon spin rotation; pressure effects; pressure techniques; quantum phase transitions; resistivity measurements; specific heat measurements; strongly correlated systems; structural phase transition; x-ray diffraction
• ISSN: 2469-9950

Lu⁢Fe4⁢Ge2 crystallizes in the Zr⁢Fe4⁢Si2-type structure, hosting chains of Fe tetrahedra giving rise to geometric frustration and low dimensionality. The compound orders antiferromagnetically at around 36 K accompanied by a simultaneous structural transition from a tetragonal phase to an orthorhombic phase. The hydrostatic pressure dependence of the magnetic and structural transitions is investigated using electrical transport, AC magnetic susceptibility, AC calorimetry, M⁢össbauer, muon-spin relaxation (μ⁢SR), and x-ray-diffraction measurements. External pressure suppresses the first-order transition to the antiferromagnetic phase (AFM1) around 1.8 GPa. The structural transition is largely unaffected by pressure and remains between 30 to 35 K for pressures up to 2 GPa. A second antiferromagnetic phase (AFM2) is observed at higher pressures. The transition from the paramagnetic to the AFM2 phase is of second-order nature and appears to be connected to the structural transition. The magnetic volume fraction obtained from μ⁢SR and M⁢össbauer measurements reveal that the entire sample undergoes magnetic ordering in both magnetic phases. In addition, similar low-temperature muon-precession frequencies in AFM1 and AFM2 phases point at similar ordered moments and magnetic structures in both phases. Our results further indicate enhanced magnetic fluctuations in the pressure-induced AFM2 phase. The experimental observations together with density functional theory calculations suggest that the magnetic- and structural-order parameters in Lu⁢Fe4⁢Ge2 are linked by magnetic frustration, causing the simultaneous magnetostructural transition.