Investigation of Magnetic and Magnetoelastic Properties of the Unconventional Heavy-fermion Compound CeCu2Ge2

Heavy-fermion compounds, high-Tc cuprates or iron pnictides are characterized by adjacent properties and a rich magnetic phase diagram with unconventional or competing states at low temperatures. CeCu2Ge2, the counterpart of the heavy-fermion superconductor CeCu2Si2, exhibits an incommensurate antiferromagnetically long-range ordered ground state with τ1 = (0.28 0.28 0.54) up to TN = 4.1 K which is strongly affected by a screening of the Ce 4f-moments by conduction electrons expressed by a Kondo temperature of TK = (6–10) K.The similar energy scales of the magnetic exchange and the Kondo effect result in a complex magnetic phase diagram with the possibility of quantum criticality at very low temperatures. The magnetic properties of CeCu2Ge2 were studied by magnetization measurements and, using the strong magnetoelastic coupling, by magnetostrictive investigations over a wide temperature range and in fields up to 50 T. Especially, the magnetostriction curves reveal clearly the details of the temperature and field dependence of the phase transitions. Here we present experimental results used for a refinement of the H − T phase diagram in [100] and [110] direction.