Structural and photoemission investigations of a new pseudo binary semimagnetic semiconductor: Sn₁-_xMn_xSe₂

Sn1−xMnxSe2 crystals have been grown by a modified Bridgman method aiming to form a new semimagnetic semiconductor whose particularity will be to have a layered CdI2-type crystal structure. This paper reports the first detailed structural and photoemission study of this new material. X-ray diffraction analysis performed on two different samples showed that only one had the expected lattice symmetry, the other one being a mixture of SnSe and α-MnSe phases. Although the preparation method of these specimen was the same they differed by the manganese quantity inserted to substitute tin in the SnSe2 lattice. This study also reveals that Mn-solubility into this lattice is not high. Photoelectron spectroscopy using X-ray and synchrotron radiation were also carried on. As it was expected, chemical states of tin and selenium in layered Sn1−xMnxSe2 are Sn4+ and Se2−, respectively. Manganese is present as Mn2+ ion, like it is the case in II1−xMnxVI materials. Investigations of layered Sn1−xMnxSe2 valence band revealed that the Mn 3d density of states is constituted of localized states at 3.5 eV of binding energy with delocalized states at lower and higher energy. Differences in Mn 3d density of states have been observed with respect to a biphased Sn1−xMnxSe2 compound.