摘要
用固相反应法制备了La0.67Sr0.08Na0.25MnO3样品.通过磁化强度-温度(M-T)曲线、电阻率-温度(ρ-T)曲线以及ρ-T拟合曲线研究了样品的输运性质及庞磁电阻(colossal magnetoresistance,CMR)效应.结果表明,ρ-T曲线和磁电阻-温度(MR-T)曲线均出现双峰现象;高温峰是伴随顺磁-铁磁(PM-FM)相变出现绝缘体-金属(I-M)相变,低温峰是颗粒界面效应;两个绝缘相输运机理不同:较低温度下(248K<T<274K),ρ(T)符合极化子的可变程跃迁模型,而在更高温区(330K<T<374K),ρ(T)符合极化子近邻跃迁模型;两个类金属相输运机理也不同:在低温区(67K<T<186K),满足ρ-T2.5关系,输运机理是自旋波散射和电-磁子散射作用,而在高温区(292K<T<304K),满足ρ-T2关系,输运机理是单磁子散射作用.
The La0.67Sr0.08Na0.25 MnO3 sample was prepared by solid-state reaction. The transport properties and CMR effect of the sample were studied through M-T curves, ρ-T curves and ρ-T fitted curves. The results show that： Both the ρ-T curves and the MR-T curve exhibit the double-peak phenomenon; the high-temperature peak corresponds to the I-M transition accompanied by the PM-FM transition, and the low-temperature peak is attributed to grain boundary effect. The two insulator phases have different transport mechanisms： in the low temperature range（248 K 〈 T 〈 274 K）, ρ（T） accords with variable-range-hopping model of polaron, while in the high temperature range（330 K 〈 T 〈 374 K）, ρ（T） accords with near- neighbor- hopping model of polaron; and the two metal-like phases also have different transport mechanisms： in the low temperature range（67 K 〈 T 〈 186 K）, ρ（T） accords with the ρ-T^2.5 relation, and the transport mechanism is the actions of spin wave scattering and electronmagneton scattering, while in the high temperature range（292 K 〈 T 〈 304 K）, ρ（T） accords with the ρ-T^2 relation, and the transport mechanism is single magneton scattering.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2007年第3期1707-1712,共6页
Acta Physica Sinica
基金
国家自然科学基金重点项目(批准号:19934003)
安徽省教育厅自然科学研究计划项目(批准号:2004KJ331)
安徽省高等学校自然科学研究项目(批准号:2005KJ234
2006KJ266B)
宿州学院教授(博士)科研启动基金(批准号:2006JB02)资助的课题.~~
关键词
庞磁电阻
金属-绝缘体转变
晶界效应
输运行为
colossal magnetoresistance, metal-insulator transition, grain boundary effect, transport behavior
