Structural and Magnetic Properties of RAg (R=La, Ce, Pr and Nd) at Hydrostatic Pressures up to 37 kbar

Abstract

Pressure-induced structural transitions and associated changes in magnetism of the light RAg have been thoroughly investigated from measurements of electrical resistivity ρ, ac magnetic susceptibility up to 37 kbar, magnetization σ up to 15 kbar and compressibility up to 3 kbar in temperatures from 1.5 K to 300 K. A cubic to tetragonal structural transition T_M is found to be induced at pressure p_c=6, 2, 10 and 30 kbar for R=La, Ce, Pr and Nd, respectively, and to increase with further increasing p at about the same rate of +13∼+16 K/kbar. The appearance of T_M and the different p_c values for the RAg are discussed on the basis of the band Jahn-Teller model. T_M is accompanied by a shift of the magnetic ordering temperature T_mag. For CeAg, another structural transition T_M is also found at p=20 kbar. The remarkably larger pressure effects of T_mag, ρ and σ are briefly discussed with recent theories of the Kondo lattice.