Polycrystalline samples of La0.4Cao.6Mn1-xCrxO3 （x = 0.00, 0.02, 0.04, 0.06） were prepared by the solid state reaction method. The influence of Cr3＋ substitution for Mn3＋ on the magnetic property and charge orderi...Polycrystalline samples of La0.4Cao.6Mn1-xCrxO3 （x = 0.00, 0.02, 0.04, 0.06） were prepared by the solid state reaction method. The influence of Cr3＋ substitution for Mn3＋ on the magnetic property and charge ordering phase of La0.4Ca0.6MnO3 was studied through the measurements of X-ray diffraction （XRD）, magnetization-temperature （M-T） curves and electron spin resonance （ESR） spectra. The experimental results indicate that the mother＇s body of La0.4Ca0.6MnO3 has very complicated magnetic structure, exhibits charge ordering phase at 258 K, and shows long-range strongly correlated charge ordering-antiferromagnetism （CO-AFM） phase from 175 to 50 K. Spin glass state appears when the temperature decreases to about 41 K. When the Cr substitution amount is x = 0.06, the charge ordering phase of the mother＇s body is de-stroyed, because the Cr3＋ substitution for Mn3＋ destroys the spin order of CE-type antiferromagnetism, and thus leads to the melting of charge ordering. It is verified experimentally that the strong coupling between charge order and spin order exists in the charge order system of CE-type antiferromagnetism.展开更多
The samples of La0.6Dy0.1Sr0.3MnO3/（Ag2O）x/2（x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.25, and 0.30） were prepared by using the solid-state reaction method.Their magnetic property, transport behavior, transp...The samples of La0.6Dy0.1Sr0.3MnO3/（Ag2O）x/2（x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.25, and 0.30） were prepared by using the solid-state reaction method.Their magnetic property, transport behavior, transport mechanism and magnetoresistance effect were studied through the measurements of magnetization-temperature（M-T） curves, ρ-T curves and the fitting of ρ-T curves.The results indicated that Ag could take part in the reaction when the doping amount is small.However, when the doping amount is comparatively large, Ag as metallic state mainly deposits on the grain boundary of La0.6Dy0.1Sr0.3MnO3, and then the system forms a two-phase composite.When the Ag doping amount is 30% mole ratio, the resistivity of the sample is one order of magnitude smaller than that of low doped samples, and its peak of magnetoresistance at 292 K and in the magnetic field of 0.2 T strengthens apparently and reaches 16.3%, which is over 7 times as large as 2.2% of La0.6Dy0.1Sr0.3MnO3.The two-phase composite system of magnetoresistance based on perovskite manganite consists of two parts：intrinsic magnetoresistance and extrinsic magnetoresistance.However, extrinsic magnetoresistance comes from spin-dependent scattering（SDS） and spin-polarized tunneling（SPT）.Magnetoresistance near TC increases due to the contribution of intrinsic magnetoresistance and extrinsic magnetoresistance formed by SDS, and magnetoresistance at low temperature is extrinsic magnetoresistance formed by SPT.展开更多
基金supported by the National Natural Foundation of China (No. 19934003)the Natural Science Research Key Program of Anhui Educational Committee (No. KJ2011A259)+2 种基金the Cultivating Base of Anhui Key Laboratory of Spintronics and Nano-materials Research Program(No. 2010YKF01No. 2010YKF04)the Professors’ and Doctors’ Research Startup Foundation of Suzhou University (Nos. 2011jb01 and 2011jb02)
基金supported by the Key Program of the National Natural Science Foundation of China (No.19934003)the Key Program of Natural Science Research of Anhui Education Department (No.KJ2011A259+3 种基金 KJ2008A34ZC)the Natural Science Research Programs of Anhui Education Department, China (No.KJ2010B229No.KJ2010B228No.KJ2009B281Z)
文摘Polycrystalline samples of La0.4Cao.6Mn1-xCrxO3 （x = 0.00, 0.02, 0.04, 0.06） were prepared by the solid state reaction method. The influence of Cr3＋ substitution for Mn3＋ on the magnetic property and charge ordering phase of La0.4Ca0.6MnO3 was studied through the measurements of X-ray diffraction （XRD）, magnetization-temperature （M-T） curves and electron spin resonance （ESR） spectra. The experimental results indicate that the mother＇s body of La0.4Ca0.6MnO3 has very complicated magnetic structure, exhibits charge ordering phase at 258 K, and shows long-range strongly correlated charge ordering-antiferromagnetism （CO-AFM） phase from 175 to 50 K. Spin glass state appears when the temperature decreases to about 41 K. When the Cr substitution amount is x = 0.06, the charge ordering phase of the mother＇s body is de-stroyed, because the Cr3＋ substitution for Mn3＋ destroys the spin order of CE-type antiferromagnetism, and thus leads to the melting of charge ordering. It is verified experimentally that the strong coupling between charge order and spin order exists in the charge order system of CE-type antiferromagnetism.
基金supported by the National Natural Foundation of China (No. 19934003) the Natural Science Research Key Program of Anhui Educational Committee (No. KJ2011A259)+3 种基金the Opening Program of Cultivating Base of Anhui Key Laboratory of Spintronics and Nanomaterials (Nos. 2010YKF04 2011YKF05)the Professors’and Doctors’Research Startup Foundation of Suzhou University (Nos. 2011jb01 2011jb02)
基金supported by the Key Program of the National Natural Science Foundation of China (No. 19934003)the Grand Program of Natural Science Research of Anhui Education Department (No. ZD2007003-1)+1 种基金the Natural Science Research Program of Universities and Colleges of Anhui Province, China (No. KJ2008A34ZC No. KJ2009A053Z)
文摘The samples of La0.6Dy0.1Sr0.3MnO3/（Ag2O）x/2（x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.25, and 0.30） were prepared by using the solid-state reaction method.Their magnetic property, transport behavior, transport mechanism and magnetoresistance effect were studied through the measurements of magnetization-temperature（M-T） curves, ρ-T curves and the fitting of ρ-T curves.The results indicated that Ag could take part in the reaction when the doping amount is small.However, when the doping amount is comparatively large, Ag as metallic state mainly deposits on the grain boundary of La0.6Dy0.1Sr0.3MnO3, and then the system forms a two-phase composite.When the Ag doping amount is 30% mole ratio, the resistivity of the sample is one order of magnitude smaller than that of low doped samples, and its peak of magnetoresistance at 292 K and in the magnetic field of 0.2 T strengthens apparently and reaches 16.3%, which is over 7 times as large as 2.2% of La0.6Dy0.1Sr0.3MnO3.The two-phase composite system of magnetoresistance based on perovskite manganite consists of two parts：intrinsic magnetoresistance and extrinsic magnetoresistance.However, extrinsic magnetoresistance comes from spin-dependent scattering（SDS） and spin-polarized tunneling（SPT）.Magnetoresistance near TC increases due to the contribution of intrinsic magnetoresistance and extrinsic magnetoresistance formed by SDS, and magnetoresistance at low temperature is extrinsic magnetoresistance formed by SPT.
