摘要:

Magnetism of bulk La1/3Nd1/3Ca1/3MnO3with a magnetoresistance ratio as high as −96&percent; in a field of 0.67 T is investigated. Two shoulders are observed on both thermal magnetization curves and magnetization isotherms. A magnetic inhomogeneity model, i.e., simultaneous occurrence of ferromagnetic La-rich domains and nonferromagnetic Nd-rich domains in the compound, is proposed. The model gives a satisfactory explanation for the experimental results. It is argued that a field-induced magnetic transition occurs in the Nd-rich phase and the coexisting La-rich phase can promote the magnetic transition. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.366210

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report on the molecular beam epitaxial growth of green (508 nm) and blue (489 nm) light-emitting diodes (LEDs) on conductive ZnSe substrates. The resistivity of the (001)-oriented ZnSe wafers was drastically reduced by a zinc extraction treatment to typical values of1×10−1 &OHgr; cm.The intensity of an additional orange band around 600 nm observed in electroluminescence depends strongly on the wavelength of the multi-quantum-well emission. This can be explained by absorption and effective re-emission in the substrate material named internal photoluminescence and was confirmed by transmission and photoluminescence experiments with the bare substrates. The LEDs with lifetimes up to 100 hours proofed to be surprisingly stable compared to the structures on undoped ZnSe substrates grown before. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.366211

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Phonons at the zone-center of wurtzite semiconductors GaN and AlN are studied theoretically within a rigid-ion model. The anisotropies of the zone-center optical phonons induced by the macroscopic electric field are investigated. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.366212

出版商:AIP    

年代:1997

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.366550

出版商:AIP    

年代:1997

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.366552

出版商:AIP    

年代:1997

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.366553

出版商:AIP    

年代:1997

数据来源: AIP