Anisotropic magnetic properties of CeAg2Ge2 single crystals

In order to investigate the anisotropic magnetic properties of CeAg2Ge2, we have successfully grown the single crystals, for the first time, by high temperature solution growth (flux) method. We have performed a detailed study of the grown single crystals by measuring their electrical resistivity, magnetic susceptibility, magnetization, specific heat and magnetoresistance. A clear anisotropy and an antiferromagnetic transition at TN = 4.6 K have been observed in the magnetic properties. The magnetic entropy reaches R ln 4 at 20 K indicating that the ground state and the first excited state are very closely spaced (a quasi-quartet state). From the specific heat measurements and crystalline electric field (CEF) analysis of the magnetic susceptibility, we have found the level splitting energies as 5 K and 130 K. The magnetization measurements reveal that the a-axis is the easy axis of magnetization and the saturation moment is μs = 1.6 μB/Ce, corroborating the previous neutron scattering measurements on a polycrystalline sample.