The influence of microscopic disorder on electron paramagnetic resonance spectra of Eu2+ ions in Pb1−xGexTe

• Published in: Journal of physics. Condensed matter 2009-10, Vol.21 (40), p.405802-405802 (6)
• Main Authors: Radzyński, T, Łusakowski, A, Świątek, K, Story, T
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron paramagnetic resonance and relaxation; Exact sciences and technology; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Physics
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/21/40/405802

In mixed crystals, because of the different ionic radii of cations or anions and the randomness in the placement of ions of different kinds, the crystal lattice is locally deformed. Such local deformations have significant influence on the ground state splitting of magnetic ions. Because this ground state splitting is responsible for the position of the electron paramagnetic resonance (EPR) lines, microscopic disorder is one of the factors which lead to the broadening of the lines, and eventually to their disappearance. This paper is devoted to semi-quantitative analysis of the influence of microscopic disorder on EPR spectra. The theory is compared against measurements performed on mono-crystalline Pb1-xGexTe epitaxial layers containing Eu2+ ions for different germanium and europium contents. With increasing germanium content we observe gradual disappearance of the EPR lines, although macroscopically, on the basis of x-ray diffraction analysis, each layer might have been considered as a perfect crystal.