Prediction In Structure And Properties Of Lu Cluster, Transition Metal Doping Si Clathlate And Eu Doping Fullerene Film

Clusters with nano-scale, fullerenes and spintronics materials have attracted considerableinteresting, for there special geometry structure, novel electronic structure and magnetismproperties. They are promising materials for applications in small spintronics materials. Withthe improvement of density functional theory and the performanc of computer, the firstprinciples calculations based on density functional theory have been applied to the study ofnew materials. In this paper, using density functional theory, we have calculated the structure,electronic and magnetism properties of Lu_n（n=2-20） cluster,3d transition metal-doped type ISi clathrates MSi₄₆（M=Mn，Fe，Co，Ni） and Eu@C₆₀monolayer adsorbed on the surface ofAg（111）. The results are as follows:（1） For Lu_n（n=2-20） cluster, when the number of atoms are smaller than16, the growthpattern of Lu_n（n＜16） cluster are based on octahedral; when the number of atoms are morethan16, the Lu_n（16≤n≤20） cluster have a new growth pattern that based on decahedral. TheLu₄，Lu₈，Lu₁₃and Lu₁₈clusters have higher stability, their binding energise are lower thenthat of their neighbors. All the Lu_n（n=2-20） clusters has small spin magnetic moments, theyare not more than4.00μB. At the same time, we found that for the clusters with the atomnumber from2to8, the magnetic moments increase in an alternating fashion. As the numberof the atom increase, an even-odd alternation between0.00μBand1.00μBwas found over therange n=9to n=20for the Lu_ncluster. A shift from ferromagnetic to ferrimagnetic orderingappears at n=5. These results provide theory assist for study the structure evolution fromcluster to bulk solids, and the magnetism and electronic properties of transition metal cluster.（2） After doping with single3d transition metal atom M （M=Mn，Fe，Co and Ni） in thetype I Si clathrates, the electronic structure and magnetic properties have changed evident.Compared with pure Si₄₆, the constant of crystal lattice in unit cell ofMSiα46andMSiβ46have a decrescence tend. Some of the silicon clathrates with a Mn or Co dopant at the centersite of a Si20cage, or a Mn, Fe or Ni dopant at the center site of a Si24cage are found to behalf-metallic materials with large magnetic moments. For Mn，Fe，Co and Ni dopant, theyhave5.00μB,4.00μB,3.00μBand2.00μBmagnetic moment, respectively. For the silicon clathrates with a Fe or Ni dopant at the center site of a Si20cage or a Co dopant at the centersite of a Si24cage display semi-metallic characters. They also have large magnetic moments.For Fe，Co and Ni dopant, they have4.00μB,3.00μBand2.00μBmagnetic moment,respectively. These results show that MSi₄₆is a fine spintronics material.（3） When the Eu@C₆₀monolayer adsorbed on the Ag（111） surface, the Eu@C₆₀monolayer induces a substrate reconstruction, the perpendicular distances between theEu@C₆₀and Ag（111） surface is smaller than that between C₆₀and Ag（111） surface by0.05.The Eu@C₆₀monolayer has the same geometry structure as that of C₆₀monolayer on Ag（111）surface. The stable structure with one hexagon of Eu@C₆₀face down and its mirror plane faceparallels to the substrate. The Eu@C₆₀/Ag（111） in unit cell has a big magnetic moment of6.80μB, which mainly come from the Eu atom according to the Mülliken charge populationanalysis. There is no chemical bonds formed between the Eu@C₆₀and Ag （111）, only0.55echarge transferred from Ag （111） to Eu@C₆₀. These results provide theory assist for study theendohedral fullerenes.