Characteristic Behavior of ESR Linewidth in Cr‐doped PbTe‐based Diluted Magnetic Semiconductors in the Vicinity of Ferromagnetic Ordering Transitionстатья
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Дата последнего поиска статьи во внешних источниках: 4 октября 2013 г.
Аннотация:Here we report on magnetization (T = 1.8–400 K,B ≤ 7 T) and X‐band ESR study (f = 9.1–9.6 GHz,T = 90–450 K) for Pb1‐yCryTe ferromagnetic semiconductor and two new PbTe‐based semiconductors Pb1‐x‐ySnxCryTe and Pb1‐x‐yMgxCryTe in the vicinity of the transition to ferromagnetic state. It was found that these semiconductors demonstrate ferromagnetism at temperatures higher than room temperature. The Curie temperature TC varies in a wide range (150–390 K) depending on the matrix composition and chromium content. In the paramagnetic phase the ESR spectra show a single asymmetrical line of Dysonian shape due to skin effect, typical of conducting materials. Regardless of matrix composition the effective g‐factor tends to the saturation value g = 2.08±0.02 and the linewidth is ΔB≈0.08 T at the highest temperature limit. Upon approaching TC from above g‐factor slowly increases, while the linewidth falls approximately two times and passes through the minimum at T∗ ≈ 1.2TC. In the vicinity of TC the ESR parameters show distinct anomalies, which were associated with presence of strong magnetic fluctuation at an onset of FM ordering.