CuO面外Sm掺杂对电子型超导体的影响  

IMPACT OF DISORDER OUTSIDE THE CuO_2 PLANES OF ELECTRON-DOPED SUPERCONDUCTORS:DIFFERENT EFFECT ON LOCALIZATION AND T_c BETWEEN GD AND SM DOPING

作　　者：杨宏顺[1] 孙成海[1] 成路[1] 王建斌[1] 许祥益[1] 柯少秦[1] 阮可青[1] 

机构地区：[1]中国科学技术大学物理系,合肥230026

出　　处：《低温物理学报》2013年第6期449-454,共6页Low Temperature Physical Letters

摘　　要：研究了Nd1.85-x Smx Ce0.15CuO4单晶的热电势S、霍耳系数RH和电阻率.在CuO2平面以外的阳离子格点引入无序,其程度是通过改变Sm含量来控制的.霍耳系数RH的测量证明这种名义掺杂没有改变载流子的密度.热电势S(T)在120K以上可用掺杂的半经验模型来分析,表明有电子的窄能带和宽能带的共存.在这个模型中,无论是态密度的带宽和有效电导率的展宽都随着x的增加而增加,而局域化的趋势随Sm掺杂增加而几乎不变.Sm掺杂对超导转变温度TC的抑制作用很小,这意味着超导TC可能与载流子局域化和巡游电子的能带结构有关.The thermopower S , Hall coefficient RH, and resistivity are studied for Nd1.85-xSmxCeo0.15CuO4 single crystals. Disorder is introduced into the cation sites outside the CuOz planes and its degree is controlled by changing Sm content. Such doping nominally does not change the doped carrier density, which is confirmed by RH. S（T） is analyzed in terms of a semiempirical model above 120K for both doping, which assumes the coexistence of a narrow electron band and a broad one. In this model, both the bandwidth for the density of states and the bandwidth of the effective conductivity broaden with increasing x, while the tendency for localization is nearly unchanged for Sm do- ping. For Sm doping Tc is nearly unchanged with increasing Sm content, which implies that the superconducting T~ may be related to the localization and the band structure of the itinerant carriers.

关 键 词：电子型超导体 热电势 局域化 

分 类 号：O511.2[理学—低温物理]