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arXiv 1408.5231cond-mat.supr-con
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Ba(1-x)NaxFe2As2(x=0.25和0.35)点接触中的Josephson效应和Andreev反射

Josephson effect and Andreev reflection in Ba(1-x)NaxFe2As2 (x=0.25 and 0.35) point contacts

V. V. Fisun, O. P. Balkashin, O. E. Kvitnitskaya, I. A. Korovkin, N. V. Gamayunova, S. Aswartham, S. Wurmehl, Yu. G. Naidyuk

摘要:

研究了基于Ba{1-x} NaxFe 2As 2($x$ =0.25和0.35)的ScS和ScN型(S超导体、C收缩体、N正常金属)点接触的I(V)特性及其一阶导数。S=Nb,Ta和Pb的ScS型光子晶体的I(V)曲线呈约瑟夫森型,具有微波诱导的Shapiro台阶,满足2 eV =hw的关系。这些PC的I_cR_N乘积(I_c-临界电流,R_N-正常态PC电阻)可达1.2mV。所有这些数据以及Pb对电极ScS光子晶体的I_c对微波功率的依赖关系表明Ba(1-x)NaxFe_2As_2中存在单重态s波型配对。根据具有Andreev反射特征的ScN型PC的dV/dI(V)曲线,计算出x=0.35的化合物的超导能隙比2Δ/kBT_c = 3.6 \pm 1。在高偏置V(远高于Δ)下对这些dV/dI(V)的分析证明了随着电压的增加,PC中的热状态发生了转变。

英文摘要:

I(V) characteristics and their first derivatives of ScS and ScN-type (S-superconductor, c-constriction, N-normal metal) point-contacts (PCs) based on Ba{1-x}NaxFe2As2 ($x$=0.25 and 0.35) were studied. ScS-type PCs with S=Nb,Ta and Pb show Josephson-like resistively shunted I(V) curves with microwave induced Shapiro steps which satisfy relation 2eV=hw. The I_cR_N product (I_c-critical current, R_N-- normal state PC resistance) in these PCs is found to be up to 1.2mV. All this data with the observed dependence of the I_c on the microwave power of ScS PCs with Pb counterelectrode indicates the presence of the singlet s-wave type pairing in Ba(1-x)NaxFe2As2. From the dV/dI(V) curves of ScN-type PCs demonstrating Andreev-reflection like features, the superconducting gap ratio 2Δ/k_BT_c = 3.6 \pm 1 for the compound with x=0.35 was evaluated. Analysis of these dV/dI(V) at high biases V, that is well above Δ, testifies transition to the thermal regime in PCs with a voltage increase.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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