Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 11: Magnetic Materials

MA 11.6: Talk

Monday, March 23, 2009, 16:30–16:45, HSZ 103

Semiconducting and half-metallic ternary rare earth compounds — •Frederick Casper and Claudia Felser — Institute of Inorganic and Analytical Chemistry,

Rare earth compounds with the LiAlSi and LiGaGe structure types have been investigated by means of band structure calculations. The LiAlSi structure type is more familiarly known as the half-Heusler structure type, whereas LiGaGe is a closely related hexagonal variant. Both structure types can be found within the same REYZ series, depending on the size of the RE element and the Y - Z bond length. A remarkable feature of some REYZ half-Heusler compounds with 18 valence electrons is that despite being composed of only metallic elements, they are semiconductors. Calculated band gaps, in comparison to experimental ones, are frequently too large, which can be attributed to some finite site disorder in the compounds. LiGaGe compounds have an additional degree of freedom, namely the degree of puckering of the layers. These compounds can become semiconducting at a certain value of puckering. Half-metallic behaviour is rarely found in this structure type. This work is supported by by DfG grant FE633/1-1 within SPP1166.