Structural, Thermal, Magnetic and Electronic Transport Properties of the LaNi2(Ge{1-x}P{x})2 System

摘要

Polycrystalline samples of LaNi2(Ge{1-x}P{x})2 (x = 0, 0.25, 0.50, 0.75, 1)were synthesized and their properties investigated by x-ray diffraction (XRD),heat capacity Cp, magnetic susceptibility chi, and electrical resistivity rhomeasurements versus temperature T. These compounds all crystallize in thebody-centered-tetragonal ThCr2Si2-type structure. The rho(T) measurementsindicate that all compositions in this system are metallic. The low-T Cpmeasurements yield a rather large Sommerfeld coefficient gamma = 12.4(2) mJ/molK^2 for x = 0 reflecting a large density of states at the Fermi energy that iscomparable with the largest values found for the AFe2As2 class of materialswith the same crystal structure. The gamma decreases approximately linearlywith x to 7.4(1) mJ/mol K^2 for x = 1. The chi measurements show nearlytemperature-independent paramagnetic behavior across the entire range ofcompositions except for LaNi2Ge2, where a broad peak is observed at 300 K fromchi(T) measurements up to 1000 K that may arise from short-rangeantiferromagnetic correlations in a quasi-two-dimensional magnetic system.High-accuracy Pade approximants representing the Debye lattice heat capacityand Bloch-Gruneisen electron-phonon resistivity functions versus T arepresented and are used to analyze our experimental Cp(T) and rho(T) data,respectively. The T-dependences of rho for all samples are well-described bythe Bloch-Gruneisen model, although the observed rho(300 K) values are largerthan calculated from this model. A significant T-dependence of the Debyetemperature determined from the Cp(T) data was observed for each composition.No clear evidence for bulk superconductivity or any other long-range phasetransition was found for any of the compositions studied.