Negative slope of resistivity-temperature curve and positive magnetoresistance in antiperovskite ZnCNi3-x Mn (x) (1.15a parts per thousand currency signxa parts per thousand currency sign1.5)

作者：Shi Lei^*; Chu Songnan; Zhao Jiyin; Wang Yang; Guo Yuqiao; Wang Cailin

来源：Applied Physics A-Materials Science & Processing, 2014, 114(3): 833-838.

DOI：10.1007/s00339-013-7693-4

In antiperovskite intermetallics ZnCNi3-x Mn (x) , the negative slope coefficient (NSC) d rho/dT of resistivity-temperature curves is observed when x=1.15,1.25,1.4,1.5. The sample with x=1.25 shows a semiconductor-like behavior in the whole temperature range of 15-290 K. By study of the magnetization, magnetoresistance, and low-temperature X-ray diffraction, it is found that Mn dopant significantly affects the physical properties of ZnCNi3-x Mn (x) by changing both the carrier density and the magnetism. The origin of the NSC d rho/dT can be ascribed to the change of hole-like carrier density, which is adjusted by Mn content. The existence of hole-like carriers can be understood rationally by the two-band model. The change of sign of magnetoresistance from positive to negative has been observed in ZnCNi3-x Mn (x) with the change of Mn content, which could be ascribed to the competition between the contribution from field-induced suppression of the thermally excited ferromagnetic spin fluctuations and the Lorentz contribution. When Mn content is low, the Lorentz contribution dominates the sign of magnetoresistance. On the other hand, when Mn content is high, the contribution from field-induced suppression of the thermally excited ferromagnetic spin fluctuations dominates the sign of magnetoresistance.

• 出版日期2014-3
• 单位中国科学技术大学