A Coexistence of Short- and Long-Range Ferromagnetic Interactions in La1-xKxMnO3 Compounds

作者：Yu, Yikyung; Dinh Chi Linh; Tran Dang Thanh^*; Pham Ngoc Dan; Nguyen Van Dang; Piao, Hong-Guang; Tartakovsy, Daniel M.

来源：IEEE Transactions on Magnetics, 2017, 53(11): 8204804.

DOI：10.1109/TMAG.2017.2706759

• Critical behavior
• ferromagnetic (FM) interaction
• perovskite manganite

In this paper, we present a detailed study on the critical behavior around the ferromagnetic (FM)-paramagnetic phase transition in La1-xKxMnO3 (LKMO) compounds with x = 0.05-0.20. Our results pointed out the easiness in controlling the value of T-C from 212 to 306 K by increasing K-doping concentration (x) from 0.05 to 0.20. Analyzing temperature and magnetic field dependences of magnetization M(T, H) at temperatures around T-C reveals all the samples undergoing the second-order phase transition. Using the modified Arrott plots, the Kouvel-Fisher, and the critical isotherm analysis methods, we have found that the values of exponent beta in the range of 0.435-0.493, which deviate from the mean-field theory (MFT) for the long-range FM interactions, indicating a coexistence of short-and long-range FM orders. We also pointed out that the critical exponents (beta and delta) depend strongly on K-concentration, shifting from values approaching those of the MFT (beta = 0.5 and delta = 3) to values approaching those of the 3-D-Heisenberg model (beta = 0.365 and delta = 4.80). In contrast, the value of the exponent gamma (= 1.222 -1.249) is almost independent of K-concentration. It suggests that K-doping favors establishing a short-range FM order in LKMO compounds.

• 出版日期2017-11
• 单位三峡大学