Presentation Information
[PCP2-07]Doping Dependence of Critical Current Density and Vortex Pinning Mechanism in Bi2Sr2CaCu2O8+δ Single Crystals
*Shigeyuki Ishida1, Junichiro Kato1,2, Shungo Nakagawa3, Takanari Kashiwagi3, Yoichi Higashi1, Yasunori Mawatari1, Nao Takeshita1, Yoshiyuki Yoshida1, Akira Iyo1, Hiraku Ogino1, Hiroshi Eisaki1, Taichiro Nishio2 (1. AIST (Japan), 2. Tokyo University of Science (Japan), 3. University of Tsukuba (Japan))
Keywords:
High-Tc cuprates,Bi2212,Single Crystal,Critical Current,Vortex Pinning
Understanding how critical current density (Jc) depends on carrier concentration (p) and which vortex pinning mechanisms contribute is a key step toward enhancing Jc and achieving broader practical applications of high-Tc cuprates. Here, we systematically evaluated the p dependence of Jc in Bi2Sr2CaCu2O8+δ (Bi2212) single crystals. In the low-temperature regime where pancake vortices are pinned, Jc exhibits two peaks at p ~ 0.12 and p ~ 0.17. This non-monotonic behavior of Jc is likely caused by changes in the pinning mechanism, then, we analyzed the magnetic-field and temperature dependence of Jc. Each temperature dependence of Jc under 1 T is decomposed into weak collective pinning (Jcwk) and strong pinning (Jcst) contributions using an expression Jc(T) = Jc0wkexp(-T/Tpwk) + Jc0stexp[-3(T/Tpst)2], where Jc0wk and Jc0st are the Jc values at 0 K, and Tpwk and Tpst are characteristic temperatures related to the pinning energy scale, for the weak collective and strong pinning contributions, respectively. The doping dependence of Jc0st and Jc0wk demonstrates that strong pinning dominates in the underdoped region (p < 0.13), whereas weak collective pinning becomes dominant in the overdoped region (p > 0.17). The strong pinning contribution, which gives rise to the unexpected Jc peak in the underdoped region (p ~ 0.12), is likely a consequence of spatial inhomogeneity of superconductivity in the CuO2 planes induced by oxygen deficiency and/or competing orders.