Structure and magnetic properties of RAlSi(R=light rare earth)

We prepared the semimetals RAl Si(R=light rare earth),and systematically study their crystal structures and magnetic properties.X-ray diffractions confirm the coexistence of the site-disordered phase with group space of I41/amd and the noncentrosymmetrically ordered phase with space group of I41 md in RAl Si alloy.The ordered phase is the main phase in RAl Si alloy.RAl Si alloys show nonmagnetic character for R=La,low temperature ferromagnetic order for R=Ce,Pr,and paramagnetic character for R=Nd,respectively.Sm Al Si shows metamagnetic transition at 10 K and ferromagnetic order at 143 K,respectively.Sm Al Si follows the van Vleck paramagnetic model in its paramagnetic region.The magnetization curves of RAl Si(R=Ce,Pr,Sm)follow the mixed model of ferromagnetism and paramagnetism,and the fitted saturation moment MSdepends on the moment of trivalent rare earth.The paramagnetic susceptibilityχof RAl Si is going up with increasing the atomic order numbers of rare earth elements.This reveals that the magnetic property of RAl Si originates from the rare earth.

Valence electron structures dependences of structural stability and properties of REX_(3)(RE=rare earth;X=In,Tl)and RE(In,Co)3 alloys

Intermetallic compounds REIn3(RE=rare earth)have attracted much attention due to their unique characteristics:crystal field effect,Kondo effect,superconductivity,heavy fermion,and antiferromagnetism,and their cobalt diluted alloys exhibit the ferromagnetic half-metallic characteristics at room temperature.In this study,an empirical electron theory(EET)is employed to investigate systemically the valence electronic structure,the thermal and magnetic properties of REX_(3) and their cobalt diluted alloys for revealing the mechanism of physical properties.The calculated bond length,melting point,and magnetic moment match the experimental ones very well.The study reveals that structural stability and physical properties of REX_(3) and their cobalt dilute alloys are strongly related to their valence electron structures.It is suggested that the structural stability and cohesive energy depend upon the covalent electron,the melting point is modulated by covalent electron pair,and the magnetic moment is originated from 3d magnetic electron.The ferromagnetic characteristics of Co-diluted REIn3 alloys is originated from the introduction of strong ferromagnetic Co atom,but,a competition is caused between the electron transition from valence electron to magnetic electron on d orbit and its reversal electron transformation with increasing the content of cobalt,which results in the formations of diluted magnetic Gd(In,Co)3 alloy with minor amount of cobalt and strong magnetic Nd(In,Co)3 alloy with doping more Co atoms.