Investigation of pressure induced ordered states in novel complex materials.

Abstract

The use of external pressure is a non-contaminant control parameter (clean) very useful to the appearance of interesting ordered states. In this project we propose to study systematically the effects of applied pressure quasi hydrostatically (P< 30 kbar) in ordered states for different compounds in the following areas: 1) Strong correlated electron systems like heavy fermions; 2) New superconductors of the family of 1-2-2 compounds (for example Fe based compounds of the type AFe2As2 (A = Ba, Sr, Ca, Eu, Li e K); 3)Double perovskites of the family R2FeIrO6 (R = La, Ca or Sr); Initially we plan to perform the following experiments under external applied pressure: electrical resistivity (P < 30 kbar) and magnetic susceptibility (P < 8 kbar) as a function of temperature ( 1.7 < T <350 K) and magnetic field (H <14 T) with pressure cells already available in our group (Grupo de Propriedades Ópticas e Magnéticas de Sólidos - GPOMS). We also plan to use the Dispersive XAS beamline of the LNLS that allows the study of XANES and EXAFS under pressure (P < 30 kbar). In the near future we plan to implement also specific heat measurements under pressure. Maintaining the philosophy of the group, beyond the investigation of the effects of applied hydrostatic pressure in the interesting compounds described here, we will continue the search for new materials in the following structural families 1-2-2, 1-1-5 and 2-1-8 that have shown to be ideal to host new heavy fermion superconductors and complex magnetic materials.