Degree of p-d hybridization in Zn1-xMnxY(Y=S, Se)and Zn1-xCoxS alloys as studied by x-ray-absorption spectroscopy

[[abstract]]We have measured x-ray-absorption near-edge-structure (XANES) spectra of the diluted magnetic semiconductors Zn1-xMnxY (Y=S,Se) and Zn1-xCoxS alloys at the Mn and Co L3,2 edge. Analysis of the Mn L3,2-edge XANES spectra for Zn1-xMnxY and Co L3,2-edge spectra for Zn1-xCoxS revealed the presence of a white-line feature in each series, whose intensity increased linearly with concentration x. The white-line feature is assigned to Mn(Co) 2p3/2 and 2p1/2photoelectron excitations to nonbonding 3d(e) states and to the relatively broadened band of Mn (Co) 3d(t2)-S 3p hybridized antibonding states for the sulfides, and to Mn 3d(t2)-Se 4p hybridized states for the selenides. The rate of increase of L3,2 white-line intensity with x is associated with the difference in the degree of p-d hybridization of states between Mn (Co) 3d and S 3p for the sulfides, and between Mn 3d and Se 4p for the selenides. Our results indicate that the magnetic-transition-metal 3d(t2)-anion p hybridization is strongest for Zn1-xCoxS, intermediate for Zn1-xMnxS and least for Zn1-xMnxSe. From separate and Co K-edge extended x-ray-absorption fine-structure measurements on Zn1-xMnxS and Zn1-xCoxS at 77 K, we found that the nearest-neighbor (NN) Mn-S (2.42 Å) and Co-S (2.30 Å) bond lengths remained essentially constant with x in these alloys, respectively. The degree of relaxation of the NN Mn (Co)-anion bond lengths is found to be directly related to the strength of p-d hybridization coupling in these alloys.[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子