Exploring thermodynamic and transport properties of strongly correlated electron systems

Abstract

The main objective of this project is theexploration and understanding of the thermodynamic and transportproperties of strongly correlated electrons systems. For thispurpose, it is planned the acquisition of a cryo-free 4Hecryostat. The latter will be equipped with a sample holder, which inturn is attached to a closed cycle 3He system. This setup willenable to perform experiments in the temperature range 0.3 - 300 Kat magnetic fields up to 12 T. In a first stage, experimental setsfor resistivity, dielectric constant and pyroelectric coefficientwill be installed in this cryostat. Materials of interest include i) the recently discovered iron-based superconductors andii) charge-transfer salts. For the Fe-based superconductors,a remarkable aspect refers to the intricate interplay betweenmagnetic ordering of Fe-3d moments, the structural phasetransition observed in underdoped samples and the superconductingdome. The possibility of preparing new materials of this family withhigher Tc than that achieved in the present (Tc = 55 K)constitute a topic of particular interest in the literature.Charge-transfer salts offer an unique possibility of studyingelectronic correlation phenomena in a "clean" environment, sincethe various phases can be tuned by means of chemical pressure and/orapplication of external pressure. Various fundamental aspects, forinstance, a detailed investigation of the transport properties ofthe pure hexagonal phase of FeSe_1-x, as well as the explorationof the charge-ordered phase in charge-transfer salts are planned. Aclose collaboration is intended with research groups in Brazil andabroad. (AU)