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Zheng L.,Baotou Normal University | Zhou M.,Baotou Normal University | Zhao J.-J.,Baotou Normal University | Cheng Z.-H.,CAS Institute of Physics | And 4 more authors.
Chinese Physics B | Year: 2011

The magnetic and electrical properties of nonmagnetic Ga+3 ion substitution for Mn site are investigated in the bilayer manganite La 1.2Sr1.8Mn2O7. When the Mn is substituted by Ga, the ferromagnetic property obviously weakens, the magnetic transition temperature decreases and a spin-glass behaviour occurs at low temperature. Meanwhile, doping causes the resistivity to dramatically increase, the metal - insulator transition temperature to disappear, and a greater magneto-resistance effect to occur at low temperature. These effects result from the fact that Ga substitution dilutes the magnetic active Mn - O - Mn network and weakens the double exchange interaction, and further suppresses ferromagnetic ordering and metallic conduction. © 2011 Chinese Physical Society and IOP Publishing Ltd.


Zheng L.,Baotou Normal University | Lu Y.,Baotou Normal University | Zhao J.-J.,Baotou Normal University | Zhang X.-Q.,CAS Institute of Physics | And 5 more authors.
Chinese Physics B | Year: 2010

The effect of Dy substitution for La site in layered manganese oxides La1.3-xDyxSr1.7Mn2O7 on the magnetic and electrical properties has been investigated. With the La 3+ substituting by Dy3+, the long range three-dimensional ferromagnetism transition and the insulator-metal transition disappear. These effects are attributed to the lattice distortion due to the substitution of the smaller Dy3+. Addtionally, the small Dy3+ is inclined to occupy the R site which is in the rock-salt layer, then the distribution of La, Sr, Dy ions in Dy-doped sample should be more orderly than that in La 1.3Sr1.7Mn2O7, so there is only one insulator-metal transition in the ρ-T curve of the sample with x = 0.05 and x = 0.1. © 2010 Chinese Physical Society and IOP Publishing Ltd.


Xing R.,Baotou Normal University | Xing R.,CAS Institute of Physics | Zhao J.-J.,Baotou Normal University | Lu Y.,Baotou Normal University | And 5 more authors.
Physica B: Condensed Matter | Year: 2011

The magnetic properties of Ca-doped Nd0.5Sr 0.5MnO3 have been studied by electron spin resonance (ESR) and dc magnetization measurements. The antiferromagnetic order and charge order are found to occur separately at TN=200 K and Tco=150 K, respectively. Compared to the undoped Nd0.5Sr0.5MnO 3, the ferromagnetic correlations are suppressed by doping of the small Ca2 ion. In addition, the antiferromagnetic transition temperature is enhanced to 200 K, which can be explained by an increase of superexchange interaction between Mn3 and Mn4 ions as their distance decreases. © 2011 Published by Elsevier B.V. All rights reserved.


He L.-M.,Baotou Normal University | Ji Y.,Baotou Normal University | Wu H.-Y.,Baotou Normal University | Xu B.,Baotou Normal University | And 4 more authors.
Chinese Physics B | Year: 2014

The effect of Eu3+ ion doping in the La sites of single-crystal La4/3Sr5/3Mn2O7 was investigated. Electron spin resonance (ESR) was applied to La4/3Sr5/3Mn2O7 and (La0.8Eu0.2)4/3Sr5/3Mn2O7 single crystals. A phase separation and phase transitions were observed from the ESR spectra data. Between 350 K and 300 K, both paramagnetic resonance (PMR) and anisotropic ferromagnetic resonance (FMR) lines were observed in the ab plane and the c axis direction, suggesting a coexistence of the paramagnetic (PM) phase and the ferromagnetic (FM) phase. The magnetization measurement reveals a spin-glass-like behavior in single-crystal (La0.8Eu0.2)4/3Sr5/3Mn2O7 below the temperature of spin freezing Tf (∼ 29.5 K). © 2014 Chinese Physical Society and IOP Publishing Ltd.


Zhou M.,Baotou Normal University | Wu H.-Y.,Baotou Normal University | Wang H.-J.,Baotou Normal University | Zheng L.,Baotou Normal University | And 3 more authors.
Physica B: Condensed Matter | Year: 2012

The physical properties of Tb 3 ions substitution at A-site are investigated in the layered manganite La 1.2Sr 1.8Mn 2O 7. A series of La 1.2-xTb xSr 1.8Mn 2O 7 (x=0, 0.05, 0.15, and 0.20) shows that doping with a Tb ion of smaller radius in La 1.2Sr 1.8Mn 2O 7 caused diffraction peaks to shift to high angle. Some samples have an impure diffraction at about 30°, but all samples form single-phase. Samples can be well indexed on a Sr 3Ti 2O7-type tetragonal structure with the space group I4/mmm. According to the M-T curves, when x≤0.05, the series of samples shows ferromagnetism at low temperatures. With increasing temperature, they have two magnetic transitions at different temperatures. When x≥0.15, the magnetizations dramatically decrease. The ρ-T curves of samples show the metal-insulator transition for x=0, 0.05, and the maximum MR values in magnetic field 5 T are 74% at about 73 K and 94% at about 86 K. When x≥0.15, the samples remain in the insulator state in the whole observed temperature range, and the maximum MR values of 86% and 69% appeared at 74 K and 42 K. © 2012 Elsevier B.V. All rights reserved.


Xing R.,Baotou Normal University | Xing R.,Inner Mongolia Key Laboratory of Magnetism and Magnetic Materials | Wan S.-L.,Baotou Normal University | Wang W.-Q.,Baotou Normal University | And 7 more authors.
Chinese Physics B | Year: 2016

A polycrystalline sample Nd0.5Sr0.3Ca0.2MnO3 is prepared by the conventional solid state reaction method. The structure and magnetic properties are investigated with x-ray diffraction (XRD) patterns, a superconducting quantum interference device (SQUID), and electron spin resonance (ESR). The sample is in single phase with the space group Pbnm symmetry. With the decrease of temperature, Nd0.5Sr0.3Ca0.2MnO3 undergoes three magnetic transitions: ferromagnetic transition at T C ≈ 210 K, charge-ordering at TCO ≈ 175 K, and antiferromagnetic transition at T N = 155 K. In addition, the activation energy Ea ≈ 52.78 meV can be extracted by curve fitting. © 2016 Chinese Physical Society and IOP Publishing Ltd.


Wang H.-J.,Baotou Normal University | Wu H.-Y.,Baotou Normal University | Zhao J.-J.,Baotou Normal University | Xing R.,Baotou Normal University | And 2 more authors.
Chinese Rare Earths | Year: 2014

Polycrystal samples of La0.5-xNdxSr0.5CoO3 (x=0, 0. 1) were prepared by solid state reaction method. The structure and magnetic properties of such samples were characterized by XRD and SQUID, respectively. Experimental results indicate that structural distortion with increasing concentration of Nd3+ weakens the electron-phonon coupling and enhances double exchange interactions via Co3+-O-Co4+, and increase the Curie temperature by 30 K. It is found in the temperature dependence of magnetization curve that the peak appearing in the ZFC curve of the x=0.1 sample is sharper than that of the undoped one. This is attributed to the weakened indiect exchange interactions between the 4f electrons of Nd with increasing temperature, which decreases the contribution from the noncollinear spin structure, and rapidly increases the magnetization. Paramagnetism-ferromagnetism transitions appear in both samples and ferromagnetic order is of short-range nature.


Wu H.-Y.,Baotou Normal University | Fan Y.-S.,Baotou Normal University | Sun Y.-B.,Baotou Normal University | Xu B.,Baotou Normal University | And 2 more authors.
Physica C: Superconductivity and its Applications | Year: 2013

The mutual interaction between an isolated superconductor (SC) vortex in a thin superconducting film and a ferromagnetic (FM) vortex in a ferromagnetic nanodisk is investigated. The interaction energy depends on the core directions. The preferred pinning site for SC vortex is at the center of the FM nanodisk if the dipoles in the core have the same perpendicular component with SC stray field, otherwise, the preferred pinning site is located at the edge of the FM nanodisk. The FM vortex core size and position change as the superconductor vortex approaches. © 2013 Elsevier B.V. All rights reserved.

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