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Li L.,Anhui Key Laboratory of Spintronic and Nanometric Materials | Li L.,Suzhou University | Wang G.,Anhui Key Laboratory of Spintronic and Nanometric Materials | Wang G.,Suzhou University | And 4 more authors.
Optik | Year: 2016

The samples of La0.6Dy0.1Sr0.3MnO3/x(CuO)(x = 0.00, 0.08, 0.12, 0.16, 0.20) were prepared by the solid-state reaction method. Electric transport property and temperature stability of magnetoresistance of the samples were studied through X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM) photograph, resistivity-temperature (ρ-T) curves in zero field and in applied magnetic field, and magnetoresistance-temperature (MR-T) curves. With the increase of CuO content, resistivity increases, and ρ-T curves exhibit a peak near 320 K, which is induced by double exchange. In the meantime, ρ-T curves exhibit a "shoulder peak" in the temperature range of 250-220 K, which is induced by boundary effect. MR-T curves exhibit a sharp peak at high temperature, MR increases continuously with temperature decreasing in low temperature range, and MR exhibits a platform in the intermediate temperature range, then the temperature stability of magnetoresistance appears. For the sample with x = 0.16, magnetoresistance keeps at 9.0 ± 0.2% without change in the temperature range of 222-272 K in the magnetic field of 0.8 T. The intrinsic magnetoresistance and extrinsic magnetoresistance of samples have been discussed, and the mechanism of temperature stability of magnetoresistance is provided. © 2015 Elsevier GmbH. Source


Li L.,Anhui Key Laboratory of Spintronic and Nanometric Materials | Li L.,Suzhou University | Wang G.-Y.,Anhui Key Laboratory of Spintronic and Nanometric Materials | Wang G.-Y.,Suzhou University | And 5 more authors.
Chinese Rare Earths | Year: 2014

The two-phase composite system of La0.80Sr0.05 Na0.15MnO3/xCuO(x=0, 0.05, 0.10, 0.15, 0.20, 0.30) was prepared by solid-state reaction method, and electric transport mechanism and temperature stability of magnetoresistance of the samples were studied through X-ray diffraction (XRD) patterns, resistivity-temperature (ρ-T) curves, ρ-T fitted curves and magnetoresistance-temperature (MR-T) curves. The results indicate that in low-temperature metal-like are-a, the electric transport mechanism is the scattering function of single magneton upon spin electron, and ρ-T curves can be fitted by ρ-T very well; MR-T curves exhibit "peak-suppressed effect" in comparatively high temperature range because extrinsic magnetoresistance induced by boundary effect dominates the system, and the magnetoresistance from the addition of intrinsic magnetoresistance and extrinsic magnetoresistance were little changed with temperature; especially the magnetoresistance of the sample with x=0.05 in the magnetic field of 0.8 T keeps at (9.9 ± 0.4)%, and basically does not change with temperature in the temperature range of 240-320 K. Therefore, the temperature stability of magnetoresistance is very good near room temperature (ΔT=80K). Source


Yang J.,Anhui Key Laboratory of Spintronic and Nanometric Materials | Yang J.,Suzhou University | Yan G.,Anhui Key Laboratory of Spintronic and Nanometric Materials | Yan G.,Suzhou University | And 10 more authors.
Rare Metals | Year: 2012

A series of (1.x)La 0.6Dy 0.1Sr 0.3MnO 3/0.5x(Sb 2O 3)(x=0.15) samples were prepared by the solid-state reaction method, and the influence of sintering temperature of the matrix on low-field magnetoresistance of (1.x)La 0.6Dy 0.1Sr 0.3MnO 3/0.5x (Sb 2O 3) was studied through the measurements of X-ray diffraction (XRD) patterns, scanning electron microscope (SEM) image, resistivity-temperature (p-T) curves, and magnetoresistance- temperature (MR-T) curves. The results indicate that for the samples with low sintering temperature of the matrix, lowfield magnetoresistance effect appears on the whole temperature range and can be explained by grain boundary effect; for the sample with high sintering temperature of the matrix, intrinsic magnetoresistance peak appears on the high-temperature range, low-field magnetoresistance effect appears on low temperature range, and the magnetoresistance in the magnetic field of 0.2 T and on the comparatively large temperature range between 280 K and 225 K hardly changes with temperature and remains at 4.8%, which can be explained by the competition between the intrinsic magnetoresistance induced by double-exchange function inside grains and the tunneling magnetoresistance (TMR) induced by grain boundary effect. The temperature stability of magnetoresistance is beneficial to the practical applications of MR. © The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg 2012. Source


Liu P.,Anhui Key Laboratory of Spintronic and Nanometric Materials | Liu P.,Suzhou University | Wang G.-Y.,Anhui Key Laboratory of Spintronic and Nanometric Materials | Wang G.-Y.,Suzhou University | And 7 more authors.
Chinese Rare Earths | Year: 2015

Pr0.4Ca0.6Mn1-xCrxO3(x = 0.00, 0.04, 0.06, 0.08, 0.10, 0.12) were prepared by the solid-state reaction method. The influences of Cr3+ substitution for Mn3+ on magnetic property and charge ordering phase of Pr0.4Ca0.6MnO3 were studied through X-ray diffraction (XRD) patterns, magnetization-temperature (M-T) curves, electron spin resonance (ESR) patterns, normalized intensity-temperature (I/I300-T) curves and peak-peak band width-temperature(△Bpp-T) curves according to ESR. The results indicate that, for the original material Pr0.4 Ca0.6MnO3, charge ordering transition temperature Tco is equal to 267 K, long-range antiferromagnetic order exists in the temperature range 205 K ~ 62 K, and a little ferromagnetic component appears in the antiferromagnetic background below 50 K; for the sample with x = 0.06, charge ordering phase has basically been destroyed, paramagnetism-antiferromagnetism transition occurs with temperature decreasing, and ferromagnetic component exists in the antiferromagnetic background; for the sample with x = 0.10, charge ordering phase has completely been destroyed, antiferromagnetic and ferromagnetic mixed phase exists below 250 K, and ferromagnetic component increases. Charge ordering phase has been destroyed because of the substitution of magnetic Cr3+ with the same electronic structure (t2g 3e00) as Mn4+ for Mn3+, the mechanism is that Cr3+ substitution for Mn3 + causes the spin order to change and then causes the charge order to be destroyed, and this indicates that strong coupling interaction between the spin order and the charge order exists in CE-type antiferromagnetic system. ©, 2015, Editorial Office of Chinese Rare Earths. All right reserved. Source

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