کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5459105 | 1516180 | 2017 | 31 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Magnetization process and specific heat properties of geometrically frustrated pyrochlores R2FeSbO7 (R3+Â =Â Dy, Y) and spin-ice magnetic phase in Dy2FeSbO7
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
فلزات و آلیاژها
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
We report the spin-ice magnetic phase in geometrically frustrated Dy2FeSbO7 from the systematic studies of dc and ac magnetization, and specific heat properties of two polycrystalline pyrochlore compounds, Dy2FeSbO7 and Y2FeSbO7. A non-magnetic Y2GaSbO7 powder is also synthesized and X-ray crystallographic structure has also been reported. DC magnetic susceptibility Ïdc(T) shows that Dy2FeSbO7 remains in Curie-type paramagnetic phase down to Tfm â 11 K, below which a small FCâZFC irreversibility and magnetic hysteresis loop provide evidence of weak ferromagnetic ordering of Fe3+-ions. The positive value of Curie-Weiss temperature is indicative of net ferromagnetic interactions among magnetic ions at low temperatures. The magnetization of Dy2FeSbO7 at 3 K saturates to the value of 5.67 μB/DyFe0.5, half of the effective moment and can be expressed by a local Ising anisotropy along the <111> D3d trigonal axes of the tetrahedral unit for polycrystalline samples. The isothermal magnetization, M(H), have been demonstrated by the Arrott plot analysis, and zero-field inverse susceptibilities are compared to the measured Ïdc(T). AC magnetic susceptibility Ïac(T) of Dy2FeSbO7 shows two distinct anomalies in its imaginary (Ïâ³) data. One of them occurs at higher temperature, Tf â¼13 K which corresponds to the ferromagnetic ordering of Fe3+-ions; another at lower temperature, Ts â¼3 K, signalling spin-ice-like freezing of Dy3+-spins in Dy2FeSbO7. The magnetic susceptibility, ÏDy(T), related to the Dy-sublattice and the measured magnetization, M(T), of Dy2FeSbO7 are reproduced satisfactorily within the framework of crystal-field theory and Weiss mean-field approximation, employing the dipolar and anisotropic exchange interactions among the Dy3+-ions. Specific heat data of Dy2FeSbO7 and Y2FeSbO7 versus T are collected at different magnetic fields. The zero-field specific heat of Dy2FeSbO7 shows a broad peak at Tpeak â 3.1 K â¼Â Ts, which gradually broadens and shifts to the higher temperature with increasing the applied field. To extract the magnetic specific heat data of these two compounds, specific heat of non-magnetic insulating Y2GaSbO7 pellet is measured and utilized to calculate the Debye temperatures of these compounds. Magnetic entropy of Dy2FeSbO7 at the zero-field equals to the spin-ice value of ÎS â 4.1 JKâ1 molâ1 around 11 K. Application of the magnetic field releases the zero-point entropy, intrinsic to the macroscopic degeneracy of the spin-ice like configurations of Dy3+-spins in Dy2FeSbO7, and hence increases the total integrated entropy.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Alloys and Compounds - Volume 714, 15 August 2017, Pages 318-330
Journal: Journal of Alloys and Compounds - Volume 714, 15 August 2017, Pages 318-330
نویسندگان
S. Nandi, Y.M. Jana, D. Swarnakar, J. Alam, P. Bag, R. Nath,