Magnetic to superconducting transition in CeCu2Si2 under pressure

Abstract We report measurements of the resistivity, performed as a function of temperature, magnetic field and hydrostatic pressure on polycrystalline samples of A-type CeCu 2 Si 2 and of CeCu 2 (Si 0.9 Ge 0.1 ) 2 , two compounds close to an antiferromagnetic (afm) quantum critical point (QCP). For an A-type polycrystalline sample of CeCu 2 Si 2 showing a (presumably afm) A-phase transition at p = 0 ( T A ≈ 0.63K), the reduction of the unit cell volume by the application of pressure ( p = 0.05GPa) results in a replacement of the A-phase by bulk superconductivity ( T C ≈ 0.52K). Consequently, increasing the unit-cell volume via substitution of Si by Ge stabilizes the magnetic phase [CeCu 2 (Si 0.9 Ge 0.1 ) 2 , T A ≈ 1.3K]. As for A-type CeCu 2 Si 2 , the magnetic contribution ρ mag vanishes at p ⩾ 0.12GPa, while T C ≈ 0.2K(p = 0) increases to T C ≈ 0.38K at p = 1.04GPa.