Sample Synthesis And Physical Properties Of Two Ce-based Compounds

Compounds containing f-electrons display a wealth of physical phenomena due to competition of the various interactions between the conduction electrons and localized magnetic moments,such as heavy fermion behavior,non-Fermi liquid behavior,magnetism,and superconductivity.Furthermore,it is of interest to tune the ground state of these materials by chemical doping,hydrostatic pressure,and magnetic fields to explore new physical phenomena.In this thesis,we mainly focus on the low temperature properties of two Ce-based systems:CeFe1-xRuxGe3(0?x?0.5)and Ce2ZnGe3.The thesis is divided into four chapters:The first chapter mainly introduces f-electron materials,the Kondo effect,the RKKY interaction and quantum phase transitions.The second chapter describes the experimental methods by briefly introducing the methods for sample preparation,as well as instruments and methods for measuring the physical properties.The third chapter presents the physical properties of polycrystalline CeRuxFe1-xGe3(0?x?0.5).CeFeGe3 is a noncentrosymmetric compound with a non-magnetic ground state.We partially substitute Ru for Ge,which does not change the crystal structure.After measuring the resistivity and specific heat of the doped compounds,we find that as more Ru atoms are doped into the CeFeGe3 lattice,the lattice volume increases,and the coherence temperature shifts to lower temperatures,indicating that the hybridization strength between the 4f and conduction electrons is reduced.The resistivity data show that the Fermi liquid region becomes narrower and non-Fermi liquid behavior is observed.The specific heat of CeFeo.5Ruo.5Ge3 does not saturate down to 2K,with C(2K)/T=420 mJ/mol K2.The appearance of non-Fermi liquid behavior shows that as we increase the Ru concentration,CeRuxFe1-xGe3 approaches a quantum critical point,suggesting that CeFeGe3 may be a good candidate for tuning towards a QCP from the non-magnetic side of the phase diagram.The fourth chapter presents the low temperature physical properties of a new compound Ce2ZnGe3.We used the flux method to grow Ce2ZnGe3 single crystals and we characterize the crystal structure,susceptibility,resistivity and specific heat.The dc susceptibility measurements show that Ce2ZnGe3 has strong ferromagnetic correlations along the c-axis with strong anisotropy.However,the ac susceptibility data shows that the peak position is shifted with increasing frequency,which is typical spin glass behavior.The freezing temperature of the spin glass is Tf= 4.91 K for H ? c,and Tf= 4.78K for H//c.This result hints at the formation of a strange magnetic ground state in which ferromagnetic ordering coexists with spin glass behavior.