Anisotropic elastic properties ofCeRhIn5

Abstract

The structure of the quasi-two-dimensional heavy fermion antiferromagnet ${\mathrm{CeRhIn}}_{5}$ has been investigated as a function of pressure up to 13 GPa using a diamond anvil cell under both hydrostatic and quasihydrostatic conditions at room $(T=295\mathrm{K})$ and low $(T=10\mathrm{K})$ temperatures. Complementary resonant ultrasound measurements were performed to obtain the complete elastic moduli. The bulk modulus $(B\ensuremath{\approx}78\mathrm{GPa})$ and uniaxial compressibilities $({\ensuremath{\kappa}}_{a}=3.96\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}{\mathrm{GPa}}^{\ensuremath{-}1}$ and ${\ensuremath{\kappa}}_{c}=4.22\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}{\mathrm{GPa}}^{\ensuremath{-}1})$ found from pressure-dependent x-ray diffraction are in good agreement with the ultrasound measurements. Unlike doping on the Rh site where ${T}_{c}$ increases linearly with the ratio of the tetragonal lattice parameters $c/a,$ no such correlation is observed under pressure; instead, a double-peaked structure with a local minimum around 4--5 GPa is observed at both room and low temperatures.