La₂Pd₂In: superconductivity and lattice properties at ambient and elevated pressures

Lattice and electronic properties of La₂Pd₂In were studied at ambient and elevated pressures so as to determine features related to a specific atomic coordination without any influence of magnetism. We describe temperature dependences of lattice parameters, heat capacity and electrical resistivity of single-crystalline La₂Pd₂In (s.g.P4/mbm) in a broad temperature range 0.09-300 K. Together with the anisotropic effect of hydrostatic pressure, showing that the lattice is more compressible in the basal plane, we can conclude that the lattice is affected by degrees of freedom of the La atoms with positions not imposed by symmetry. The lattice anisotropy is smaller than that found for isostructural ferromagnet Ce₂Pd₂In. The equilibrium bulk modulusB₀= (48 ± 3) GPa was determined on the basis of individual linear compressibilities. Measurement of electrical resistivity indicated a superconducting state belowT= 0.59 K with a low critical field 0.005 T atT= 380 mK. The onset of superconducting state as a bulk property of La₂Pd₂In was confirmed by measurements of specific heat and AC magnetic susceptibility. Experimental data can be accounted by first-principles electronic-structure calculations based on density-functional theory. The measured Sommerfeld coefficientγ= 10.6 mJ mol^-1 K^-2, only marginally exceeding the calculatedγ= 9.34 mJ mol^-1 K^-2, indicates only weak electronic correlations.