Infrared absorption spectra of La0.67-xPrxCa0.33MnO3 （x= 0, 0.18 and 0.36） are experimentally studied in the temperature range 20 -300K. Absorption peak splitting corresponding to the stretching oscillation of the M...Infrared absorption spectra of La0.67-xPrxCa0.33MnO3 （x= 0, 0.18 and 0.36） are experimentally studied in the temperature range 20 -300K. Absorption peak splitting corresponding to the stretching oscillation of the Mn-O bond, together with a shift of peak position, is observed below the Curie temperature. These features weaken and even disappear as the samples are warmed up to the Curie temperature, which indicates that this anomaly may be a result of phase separation in the compounds.展开更多
The magneto-optical Kerr effect of La0.7Ca0.3MnO3 at low temperature in far-infrared terahertz and mid-infrared region from 0.2 to 1.2 eV is theoretically investigated by means of the Drude model. The complex con-duct...The magneto-optical Kerr effect of La0.7Ca0.3MnO3 at low temperature in far-infrared terahertz and mid-infrared region from 0.2 to 1.2 eV is theoretically investigated by means of the Drude model. The complex con-ductivity and dielectric constants are obtained. The spectra of Kerr rotation with different external magnetic fields B and temperatures T are numerically analyzed. A large Kerr rotation in mid-infrared region could be explained as the incoherent hopping motion of polarons.展开更多
Manganese oxides with a perovskite-type Re_(1-x)D_xMnO_3(Re:heavy rare-earth elements,D:divalent alkali metal)structure have attracted interest because of the complex interaction between their electrons,lattices,and s...Manganese oxides with a perovskite-type Re_(1-x)D_xMnO_3(Re:heavy rare-earth elements,D:divalent alkali metal)structure have attracted interest because of the complex interaction between their electrons,lattices,and spins[1-5].Generally,manganese oxides with the structure Re_(1-x)D_xMnO_3 have special properties.For example,the half-metallic manganites,such as La_(2/3)Sr_(1/3)MnO_3 and La_(2/3)Ca_(1/3)MnO_3,wherein the conduction electrons are completely spin polarized。展开更多
The electrical resistance in zero magnetic field and magnetoresistance in different external magnetic fields have been measured in a temperature range of 77-300 K. It is found that the temperature dependence of magnet...The electrical resistance in zero magnetic field and magnetoresistance in different external magnetic fields have been measured in a temperature range of 77-300 K. It is found that the temperature dependence of magnetoresistance can be well described by a phenomenological formula of ρ(T)=(1σ(T)= (1α(M/M s) 2+βexp(-E 0/k BT), where the fitting parameters α,β vary as the external magnetic field H changes, E 0 is the activation energy, E 0/k B =1160 K, M s is the saturation magnetization, the temperature and magnetic field dependence of M/M s is obtained by the mean-field expression.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos G50225209 and G50271023, the Key Foundation of Education Ministry of China under Grant G02017 and the Natural Science Foundation of Hebei Province under Grant No G503031.
文摘Infrared absorption spectra of La0.67-xPrxCa0.33MnO3 （x= 0, 0.18 and 0.36） are experimentally studied in the temperature range 20 -300K. Absorption peak splitting corresponding to the stretching oscillation of the Mn-O bond, together with a shift of peak position, is observed below the Curie temperature. These features weaken and even disappear as the samples are warmed up to the Curie temperature, which indicates that this anomaly may be a result of phase separation in the compounds.
基金Supported by the Major Project of Knowledge Innovation Project of Chinese Academy of Science (No. KJCX2SW-N02)
文摘The magneto-optical Kerr effect of La0.7Ca0.3MnO3 at low temperature in far-infrared terahertz and mid-infrared region from 0.2 to 1.2 eV is theoretically investigated by means of the Drude model. The complex con-ductivity and dielectric constants are obtained. The spectra of Kerr rotation with different external magnetic fields B and temperatures T are numerically analyzed. A large Kerr rotation in mid-infrared region could be explained as the incoherent hopping motion of polarons.
基金supported by the Major State Basic Research Development Program(Grant No.2013CB922302)the National Natural Science Foundation of China(Grant No.11374320)
文摘Manganese oxides with a perovskite-type Re_(1-x)D_xMnO_3(Re:heavy rare-earth elements,D:divalent alkali metal)structure have attracted interest because of the complex interaction between their electrons,lattices,and spins[1-5].Generally,manganese oxides with the structure Re_(1-x)D_xMnO_3 have special properties.For example,the half-metallic manganites,such as La_(2/3)Sr_(1/3)MnO_3 and La_(2/3)Ca_(1/3)MnO_3,wherein the conduction electrons are completely spin polarized。
文摘The electrical resistance in zero magnetic field and magnetoresistance in different external magnetic fields have been measured in a temperature range of 77-300 K. It is found that the temperature dependence of magnetoresistance can be well described by a phenomenological formula of ρ(T)=(1σ(T)= (1α(M/M s) 2+βexp(-E 0/k BT), where the fitting parameters α,β vary as the external magnetic field H changes, E 0 is the activation energy, E 0/k B =1160 K, M s is the saturation magnetization, the temperature and magnetic field dependence of M/M s is obtained by the mean-field expression.
