Development of magnetic order in CeCu2(Si1-xGex)2 as a function of hybridization

Abstract In the alloy system CeCu 2 (Si 1− x Ge x ) 2 phase A, i.e., antiferromagnetic order at x > 0 , evolves from a heavy-fermion state at x = 0 , where T A → 0 and non-Fermi-liquid effects are observed. Here, we present the results of specific-heat measurements on a CeCu 2 (Si 0.9 Ge 0.1 ) 2 polycrystal as a function of external magnetic field ( 0 ⩽ B ⩽ 8T) and hydrostatic pressure ( 0 ⩽ p ⩽ 1GPa). In this sample a magnetic ( T A = 1.4K) and a superconducting (sc) phase ( T C = 0.21K) have been observed at p = 0. Our finite-pressure results indicate a subtle difference between steric and chemical effects. At p = 1.0GPa superconductivity sets in at T C ⩽ 0.55K, while T A remains almost unchanged.