Metal Flux Crystal Growth Technique in the Determination of Ordered Superstructure in EuInGe

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• 作者：Udumula Subbarao ; Ashly Sebastian ; Sudhindra Rayaprol ; C. S. Yadav ; Axel Svane ; G. Vaitheeswaran ; Sebastian C. Peter
• 刊名：Crystal Growth & Design
• 出版年：2013
• 出版时间：January 2, 2013
• 年：2013
• 卷：13
• 期：1
• 页码：352-359
• 全文大小：433K
• 年卷期：v.13,no.1(January 2, 2013)
• ISSN：1528-7505

文摘

High quality single crystals of EuInGe were grown from the reaction run with excess indium. X-ray diffraction investigations showed that EuInGe crystallizes with a pronounced subcell structure, superstructure of the ThSi₂ type: Pnma space group, a = 4.9066(10) 脜, b = 3.9834(8) 脜 and c = 15.964(3) 脜. However, the powder X-ray pattern reveals weak superstructure reflections, and the inclusion of additional reflections in the analysis points to a new type of structural arrangement, in a monoclinic system, P2₁/c space group, a = 7.9663(16) 脜, b = 4.9119(10) 脜, c = 16.465(5) 脜, and 尾 = 104.03掳. Magnetization measurements carried out as a function of temperature show multiple magnetic transitions at 13, 25, 44, and 70 K. In the temperature region above 100 K, the Curie鈥揥eiss law is followed indicating a paramagnetic state of the sample. Magnetic moments deduced from this region suggest europium to be in a divalent state, which was further confirmed by ¹⁵¹Eu M枚ssbauer spectroscopic measurements. Experiments were accompanied by first-principles density functional calculations using the full-potential linear muffin-tin orbital method within the local density approximation (LSDA) and including the onsite Coulomb interaction (LSDA+U) for the Eu-f states. The density of states shows a pronounced pseudo gap feature around the Fermi level. The inclusion of a Hubbard U has only a minor effect on the band structure. From the calculated total energies the P2₁/c structure is favorable by 25 meV per formula unit when compared to the Pnma subcell structure.