Icosahedral quasicrystal ${\mathrm{Al}}_{71}{\mathrm{Pd}}_{21}{\mathrm{Mn}}_{08}$ and its ${\mathrm{\xi }}^{\prime }$ approximant:  Linear expansivity, specific heat, magnetic susceptibility, electrical resistivity, and elastic constants

Linear thermal expansivity (α, 1–300 K), heat capacity ${(C}_p,$ 1–108 K), magnetic susceptibility (χ, 1–300 K), and electrical resistivity (ρ, 1–300 K) measurements are reported for a single-grain $i-{\mathrm{Al}}_{71}{\mathrm{Pd}}_{21}{\mathrm{Mn}}_{08}$ quasicrystal and its ${\mathrm{Al}}_{72}{\mathrm{Pd}}_{25}{\mathrm{Mn}}_{03}$ approximant, and 300 K elastic constants for the quasicrystal. The approximant $\alpha$ $\left({\alpha }_{\mathrm{Ap}}\right)$ and $C_p$ ${(C}_{\mathrm{pAp}})$ data show “metallic” behavior, while the previously reported onset of a transition to a spin-glass state ${(T}_f<1.8\mathrm{}\mathrm{K})$ dominates ${\alpha }_Q$ and $C_{\mathrm{pQ}}$ below 11 K. $C_{\mathrm{pAp}}$ and $C_{\mathrm{pQ}}$ superimpose above 16 K when plotted vs $T/{\Theta }_0$ using the experimental ${\Theta }_{0Ap}=455\mathrm{}\left(3\right)\mathrm{}\mathrm{K}$ and an adjusted ${\Theta }_{0ApQ}=480\mathrm{}\left(4\right)\mathrm{}\mathrm{K}.$ The 300 K elastic constants extrapolated to $T=0\mathrm{}$ give ${\Theta }_{0Q}^{\mathrm{el}}=505\mathrm{}\left(1\right)\mathrm{}\mathrm{K},$ suggesting that the normalization is valid only above 16 K. The lattice contribution to $C_{\mathrm{pAp}}$ (and, indirectly, $C_{\mathrm{pQ}})$ shows strong (unique) deviations from Debye-like behavior (+3% at 0.84 K for the $C_{\mathrm{pAp}}$ data fit). The various Grüneisen parameters (Γ) that are calculated from these data all are positive and normal in magnitude except for a large limiting approximant lattice value, ${\Gamma }_{0Ap}^{\mathrm{lat}}=11.3\mathrm{}$, which may be related to the large dispersion effects in $C_p.$ For the approximant, the combination of anisotropic and large resistivities, a small diamagnetic susceptibility, and a “large” linear (electronic) contribution to $C_{\mathrm{pAp}}$ $({\gamma }_{\mathrm{Ap}}=0.794\mathrm{}\mathrm{mJ}/{\mathrm{mol}\mathrm{}\mathrm{K}}^2)$ suggests the existence of a pseudogap in the electronic density of states. The unusually large, highly volume dependent, dispersion at low temperatures for the quasicrystal and its approximant are not consistent with inelastic neutron scattering and other data, and raise questions about the role of phonons in quasicrystals. The present 300 K resistivities can be used with a published correlation to estimate ${\gamma }_Q\approx 0.25\mathrm{mJ}/{\mathrm{mol}\mathrm{}\mathrm{K}}^2.$