摘要
利用水热法和旋涂工艺制备Co2+掺杂CdO基稀磁半导体纳米薄膜,研究样品的微观结构及电磁性能等。结果表明:样品是具有岩盐矿结构的CdO晶体结构,薄膜中粒子的平均粒径约20nm,且随Co摩尔(下同)掺量的增加而减小。样品中Co离子为正二价,属替位掺杂;样品呈现出明显的室温铁磁性,饱和磁矩随Co2+掺量的增加先增大后减小,在Co2+掺量为4.33%时达到最大值。样品的电导率随Co2+掺量的增加先减小后微弱增大,在Co2+掺量约为6%时达到最小值。磁电阻效应测量结果表明:样品呈现出室温的正磁电阻效应,磁电阻随Co2+掺量的增加先增大后减小,在Co2+掺量约为7%时达到最大值。利用Ruderman-Kittel-Kasuya-Yoshida(RKKY)机制、间接超交换机制和直接超交换机制等模型合理解释样品的铁磁性起源和磁电阻效应产生的物理机制。
The Co^2 ＋doped CdO diluted magnetic semiconductor nanofilms were synthesized using the hydrothermal method and spin-coating technique.The microstructure,magnetic and electronic properties were investigated.The results show that samples have the structure of rock salt,similar to CdO crystal.The average size of particles in the films is about 20 nm and becomes smaller with increasing the dosages of Co^2 ＋in mole.The Co ions are in a bivalent state and doped into the CdO nanocrystals by replacing Cd ^2＋ sites in crystal lattices.The samples exhibit obvious room-temperature ferromagnetism.The saturated magnetic moment firstly increases and then decreases as the Co^2 ＋dosage is increased,and reaches its maximum value at the Co ^2＋dosage（mole fraction,the same below） of 4.33%.The conductivity of the films first decreases and then slightly increases when the Co^2 ＋dosage is increased,and reaches its minimum value when the Co ^2＋ dosage is at 6%.The samples exhibit a magnetoresistance effect at room temperature.The magnetoresistance first increases and then decreases as the Co^2 ＋dosage is increased,and reaches its maximum value at a Co ^2＋dosage of about 7%.The origin and physical mechanism of the ferromagnetism and magnetoresistance are explained by the Ruderman-Kittel-Kasuya-Yoshida（RKKY） mechanism,indirect exchange mechanism and direct exchange mechanism.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2010年第3期404-408,共5页
Journal of The Chinese Ceramic Society
基金
国家自然科学基金(10774070
50972055)
江苏省自然科学基金(BK2008024)资助项目
关键词
氧化镉
稀磁半导体
纳米薄膜
水热法
铁磁性
磁电阻
cadmium oxide
diluted magnetic semiconductor
nanofilms
hydrothermal method
ferromagnetism
magnetoresistance
