We review colossal magnetoresistance in single phase manganites, as related to the field sensitive spin-charge interactions and phase separation; the rectifying property and negative/positive magnetoresistance in mang...We review colossal magnetoresistance in single phase manganites, as related to the field sensitive spin-charge interactions and phase separation; the rectifying property and negative/positive magnetoresistance in manganite/Nb：SrTio3 p-n junctions in relation to the special interface electronic structure; magnetoelectric coupling in manganite/ferroelectric structures that takes advantage of strain, carrier density, and magnetic field sensitivity; tunneling magnetoresistance in tunnel junctions with dielectric, ferroelectric, and organic semiconductor spacers using the fully spin polarized nature of manganites; and the effect of particle size on magnetic properties in manganite nanoparticles.展开更多
The Gd substituting effects for La in La0.67Ca0.33MnO3 has been studied. With increasing the substituting amount of Gd, the phase transition temperature of metal-isolator for the samples decreases, the corresponding p...The Gd substituting effects for La in La0.67Ca0.33MnO3 has been studied. With increasing the substituting amount of Gd, the phase transition temperature of metal-isolator for the samples decreases, the corresponding peak resistivity increases, the Curie temperature decreases monotonically. The substitution of La-Ca-Mn-O with 11% Gd for La improved the magnetoresistance ratio by an order of magnitude. The effects of substituting Gd can be explained in terms of the lattice effects. An irreversible MR behaviour was observed in Gd-substituting compounds. This effect became marked when the substituting amount of Gd was greater than 7%. A maximum irreversible increment of MR ratio as large as 91% was obtained when Gd substituting amount was 11%.展开更多
The magnetic and electrical transport properties of the colossal magnetoresistance material La_(2/3)Ca_(1/3)MnO_3 were studied. It is found that the insulator-metal transition is well consistent with the paramagnetic-...The magnetic and electrical transport properties of the colossal magnetoresistance material La_(2/3)Ca_(1/3)MnO_3 were studied. It is found that the insulator-metal transition is well consistent with the paramagnetic-ferromagnetic transition,and shifts to higher temperature with increasing applied magnetic field. These results suggest that the transport properties are triggered by the magnetic structure transition and consequently result in a CMR near T _C.展开更多
Electrical transport properties of the La0.7Ca0.3MnO3nanoparticles have been inves-tigated in the temperature range 300 to 9 K as a function of magnetic field. Samples were pre-pared by auto-ignition method. In low te...Electrical transport properties of the La0.7Ca0.3MnO3nanoparticles have been inves-tigated in the temperature range 300 to 9 K as a function of magnetic field. Samples were pre-pared by auto-ignition method. In low tempera-ture regime from 40 to 9 K, an increase in the resistivity has been observed. This effect is found to decrease as magnetic field is increased. It is assumed that these effects are due to the magnetic contacts between the nanoparticles.展开更多
Magnetocaloric and colossal magnetoresistance effects of the layered perovskite La 1.4 Sr 1.6 Mn 2 O 7 compound have been studied.A broad peak of magnetic entropy change （-△S M） is found above the Curie temperature...Magnetocaloric and colossal magnetoresistance effects of the layered perovskite La 1.4 Sr 1.6 Mn 2 O 7 compound have been studied.A broad peak of magnetic entropy change （-△S M） is found above the Curie temperature （T C =120 K）,which can be associated with the existence of two-dimensional short range ferromagnetic order.Additionally,the curvilinear shape of-△S M for layered perovskite is quite different from that of the Ln 1-x A x MnO 3 probably arising from magnetocrystalline anisotropy.At the same time,a wide peak of colossal magnetoresitance effect near T C is found in the layered provskite La 1.4 Sr 1.6 Mn 2 O 7.展开更多
The magnetocaloric effect in the colossal magnetoresistance material La_(2/3)Ca_(1/3)MnO_3 was studied. From the measurements of temperature dependence of magnetization in various magnetic fields, the large magnetic e...The magnetocaloric effect in the colossal magnetoresistance material La_(2/3)Ca_(1/3)MnO_3 was studied. From the measurements of temperature dependence of magnetization in various magnetic fields, the large magnetic entropy change associated with the ferromagnetic-paramagnetic transition was discovered. This result suggests that perovskite manganites are suitable candidates as working substance in magnetic refrigeration technology.展开更多
The anomalous photovohaic effect was studied in epitaxial La0.8Sr0.2MnO3 films by laser molecular beam epitaxy. It is demonstrated that the signal polarity is reversed when the films are irradiated through the substra...The anomalous photovohaic effect was studied in epitaxial La0.8Sr0.2MnO3 films by laser molecular beam epitaxy. It is demonstrated that the signal polarity is reversed when the films are irradiated through the substrate rather than the film. Electron microdiffration and high-resolution imaging reveal that La0.8Sr0.2MnO3 thin film is epitaxially grown on the substrate, and the oriented microdomains run through the thickness of film, forming a columnar structure. Detailed investigations of the distribution of electric potential in the film surface with respect to the location of laser spot suggest that the anomalous photovoltaic response is due to an asymmetry of oriented microdomains in thin film. Under ultraviolet laser irradiation, the electron-hole pairs are excited in the manganese oxide film. The asymmetry of microdomains generates a built-in electric field and induces an asymmetric transport of the excited carriers, and hence a a photo voltage signal is obtained.展开更多
基金supported by the National Natural Science Foundation of Chinathe National Basic Research Program of China(Grant Nos.2012CB922003,2011CBA00102,and 2009CB929502)
文摘We review colossal magnetoresistance in single phase manganites, as related to the field sensitive spin-charge interactions and phase separation; the rectifying property and negative/positive magnetoresistance in manganite/Nb：SrTio3 p-n junctions in relation to the special interface electronic structure; magnetoelectric coupling in manganite/ferroelectric structures that takes advantage of strain, carrier density, and magnetic field sensitivity; tunneling magnetoresistance in tunnel junctions with dielectric, ferroelectric, and organic semiconductor spacers using the fully spin polarized nature of manganites; and the effect of particle size on magnetic properties in manganite nanoparticles.
基金This work was supported by the State Key Project of Funda-mental Research (G19980613010) the National Scientific and Technological Department of China.
文摘The Gd substituting effects for La in La0.67Ca0.33MnO3 has been studied. With increasing the substituting amount of Gd, the phase transition temperature of metal-isolator for the samples decreases, the corresponding peak resistivity increases, the Curie temperature decreases monotonically. The substitution of La-Ca-Mn-O with 11% Gd for La improved the magnetoresistance ratio by an order of magnitude. The effects of substituting Gd can be explained in terms of the lattice effects. An irreversible MR behaviour was observed in Gd-substituting compounds. This effect became marked when the substituting amount of Gd was greater than 7%. A maximum irreversible increment of MR ratio as large as 91% was obtained when Gd substituting amount was 11%.
文摘The magnetic and electrical transport properties of the colossal magnetoresistance material La_(2/3)Ca_(1/3)MnO_3 were studied. It is found that the insulator-metal transition is well consistent with the paramagnetic-ferromagnetic transition,and shifts to higher temperature with increasing applied magnetic field. These results suggest that the transport properties are triggered by the magnetic structure transition and consequently result in a CMR near T _C.
文摘Electrical transport properties of the La0.7Ca0.3MnO3nanoparticles have been inves-tigated in the temperature range 300 to 9 K as a function of magnetic field. Samples were pre-pared by auto-ignition method. In low tempera-ture regime from 40 to 9 K, an increase in the resistivity has been observed. This effect is found to decrease as magnetic field is increased. It is assumed that these effects are due to the magnetic contacts between the nanoparticles.
基金supported by the National Natural Science Foundation of China (Nos. 50331040 and 60171043)
文摘Magnetocaloric and colossal magnetoresistance effects of the layered perovskite La 1.4 Sr 1.6 Mn 2 O 7 compound have been studied.A broad peak of magnetic entropy change （-△S M） is found above the Curie temperature （T C =120 K）,which can be associated with the existence of two-dimensional short range ferromagnetic order.Additionally,the curvilinear shape of-△S M for layered perovskite is quite different from that of the Ln 1-x A x MnO 3 probably arising from magnetocrystalline anisotropy.At the same time,a wide peak of colossal magnetoresitance effect near T C is found in the layered provskite La 1.4 Sr 1.6 Mn 2 O 7.
文摘The magnetocaloric effect in the colossal magnetoresistance material La_(2/3)Ca_(1/3)MnO_3 was studied. From the measurements of temperature dependence of magnetization in various magnetic fields, the large magnetic entropy change associated with the ferromagnetic-paramagnetic transition was discovered. This result suggests that perovskite manganites are suitable candidates as working substance in magnetic refrigeration technology.
文摘The anomalous photovohaic effect was studied in epitaxial La0.8Sr0.2MnO3 films by laser molecular beam epitaxy. It is demonstrated that the signal polarity is reversed when the films are irradiated through the substrate rather than the film. Electron microdiffration and high-resolution imaging reveal that La0.8Sr0.2MnO3 thin film is epitaxially grown on the substrate, and the oriented microdomains run through the thickness of film, forming a columnar structure. Detailed investigations of the distribution of electric potential in the film surface with respect to the location of laser spot suggest that the anomalous photovoltaic response is due to an asymmetry of oriented microdomains in thin film. Under ultraviolet laser irradiation, the electron-hole pairs are excited in the manganese oxide film. The asymmetry of microdomains generates a built-in electric field and induces an asymmetric transport of the excited carriers, and hence a a photo voltage signal is obtained.
