0000000000411745
AUTHOR
Yoji Koike
Carrier-dependentT c -suppression in Cu-site substituted high-T c cuprates
We studied theTc-suppression by Cu-site substitution in Bi2Sr2Ca1−xYx(Cu1−zMz)2O8+δ (Bi-2212) with M=Fe, Co, Ni, Zn and in Bi2Sr1.6La0.4Cu1−zMzO6+δ (Bi-2201) with M=Co, Zn under variation of the hole concentrationp. We found a distinct behaviour between the underdoped and overdoped side of theTc-p phase diagram. Only in the overdoped regime,Tc is scaling asTc(p,z)=Tc(p,0)g(z) with ap-independent scaling functiong(z). We demonstrate the universality of this distinction in p-type high-Tc cuprates by comparison with publications on the La-214 and Y-123 systems and apply the scaling law to compare Bi2Sr2Ca(Cu1−zCoz)2O8+δ with the intercalation compound IBi2Sr2Ca(Cu1−zCoz)2O8+δ. The results are …
Anomalous behavior of the second magnetization peak inLa1.81Sr0.19CuO4single crystals: Possible influence of two-band superconductivity
We report an anomalous temperature $T$ variation of the field ${H}_{\text{on}}$ for the onset of the second magnetization peak in ${\text{La}}_{1.81}{\text{Sr}}_{0.19}{\text{CuO}}_{4}$ single crystals with the external magnetic field $H$ oriented parallel to the $c$ axis. While the peak field ${H}_{p}$ has a continuous decrease with increasing $T$, ${H}_{\text{on}}$ exhibits a sudden decrease for $T\ensuremath{\sim}11--15\text{ }\text{K}$. This behavior appears to be related to the particular $T$ dependence of the superfluid density in the case of two-band superconductivity affecting the $T$ variation of the elastic energy of the vortex system at low $H$.