Co掺杂对铁磁金属La0.8Sr0.2MnO3磁电阻影响机理

通过对La_0.8Sr_0.2Mn_1-yCo_yO₃(y≤02)饱和磁矩和输运的测量，研究了Co对La_0.8Sr_0.2MnO₃的磁电阻影响机制.结果表明，在La_0.8Sr_0.2Mn_1-yCo_yO₃（y≤02）中Co³⁺离子是低自旋态.由于Mn³⁺—O—Co³⁺—O—Mn³⁺类型的磁交换与Mn³⁺-Mn⁴⁺离子间双交换作用相比较弱，Curie温度T_C附近的磁电阻随着Co掺杂量的增加而降低.与此相反，由于Co²⁺离子与e_g巡游电子的反铁磁交换耦合作用，低温区间的磁电阻随着Co掺杂量的增加而升高. 关键词： 低自旋 磁电阻 磁交换作用

Mechanism of magnetoresistance impacted by Co doped in La_(0.8)Sr_(0.2)MnO_3 ferromagnetic metallic

Through measurement of saturation magnetic moment and transport of La_(0.8)Sr_(0.2)Mn_(1-y)Co_yO_3(y≤0.2),the mechanism of magnetoresistance(MR)impacted by Co doping is investigated.The results show that Co~(3+) is in the lowspin state in La_(0.8)Sr_(0.2)Mn_(1-y)Co_yO_3(y≤0.2).The magnetic exchange interactions of the type Mn~(3+)-O-Co~(3+)-O-Mn~(2+) is weaker than that of the double exchange interaction between Mn~(3+)-Mn~(4+),and the magnetoresistance near the Curie temperature T_c decreases with the increase of Co concentration.On the contrary,low-temperature magnetoresistance increases with the increase of Co concentration owing to the antiferromagnetic exchange coupling between Co~(2+) and eg itinerant electron.