Quantum Criticality of the Quasi-One-Dimensional Heavy Fermion Material YbFe5P3

Quantum criticality has been an organizing principle to explain the behavior of many families of quantum materials including the high-temperature cuprate and iron-based superconductors and f-electron heavy fermion compounds. A central, unresolved issue is the role of quantum fluctuation dimensionality on the properties of the system. Most work to date has focused on quantum criticality with two-dimensional (2-D) and three-dimensional (3-D) fluctuations. Strong quantum fluctuations are expected in quasi-1-D materials and have recently been explored in 1-D f-electron materials such as CeRh6Ge4 [1], Yb2Pt2Pb [2], and YbAlO3 [3].

YbFe5P3 crystallizes in the orthorhombic YCo5P3 structure type [4] with 1-D Yb chains along the b-axis with an Yb-Yb distance of 3.65 Å, while the inter-chain Yb-Yb spacing is 5.61 Å. Below about 5 K, the electrical resistivity reflects the presence of strong quantum fluctuations. Specific heat measurements show a similar strong enhancement at low temperatures reaching a constant value of C/T=1.5 J/mol K2 below T = 0.5 K, indicating a heavy Fermi liquid state. No magnetic ordering is observed down to 80 mK. Chemical substation of Co or Ru for Fe drives YbFe5P3 to a quantum critical point. A magnetically ordered state is found for Co concentrations greater than 20%, beyond the quantum critical point. In this talk, I will describe the physical properties of the quasi-1D heavy fermion material YbFe5P3 and the nature of quantum criticality in Yb(Fe1-xMx)5P3 (M=Co, Ru).

[1] B. Shen et al. Nature 579, 51 (2020); H. Kotegawa et al, JPSJ 88, 093702 (2019)

[2] L. S. Wu et al. Science 352, 1206 (2016)

[3] L. S. Wu et al. Nature Communications 10, 698 (2019)

[4] W. Jeitschko et al. J. Solid State Chem. 55, 331 (1984)