Measurement of the current-phase relation of superconductor/ferromagnet/superconductor π Josephson junctions
Measurement of the current-phase relation of superconductor/ferromagnet/superconductor π Josephson junctions
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超导体/铁磁体/超导体π约瑟夫森结电流相位关系的测量
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
V. Ryazanov
中科院分区：
文献类型：
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作者：
S. Frolov;D. Harlingen;V. Oboznov;V. Bolginov;V. Ryazanov
我们测量了超导体-铁磁-超导体（SFS）约瑟夫森结的电流-相位关系（CPR）作为温度的函数。通过将结并入与直流SQUID耦合的超导环路中来确定CPR，从而可以测量结相位差。我们发现$mathrm{Nb} ext{ensuremath{-}}{mathrm{Cu}}_{0.47}{mathrm{Ni}}_{0.53} ext{ensuremath{-}}}mathrm{Nb}$ Josephson结的临界电流随势垒厚度$ensuremath{sim}22phantom{
rule{0。3em}{0ex}}mathrm{nm}$改变符号$Tl{T}_{ensuremath{pi}}ensuremath{sim}2—4phantom{
rule{0。3em}{0ex}}mathrm{K}$，表示该结点变成$ensuremath{pi}$ Josephson结点。在几个理论预测的CPR中，我们没有发现${T}_{ensuremath{pi}}$附近二阶约瑟夫森隧道的证据。
We present measurements of the current-phase relation (CPR) of superconductor-ferromagnet-superconductor (SFS) Josephson junctions as a function of temperature. The CPR is determined by incorporating the junction into a superconducting loop coupled to a dc SQUID, allowing measurement of the junction phase difference. We find that the critical current of $mathrm{Nb} ext{ensuremath{-}}{mathrm{Cu}}_{0.47}{mathrm{Ni}}_{0.53} ext{ensuremath{-}}mathrm{Nb}$ Josephson junctions with barrier thickness $ensuremath{sim}22phantom{
ule{0.3em}{0ex}}mathrm{nm}$ changes sign at $Tl{T}_{ensuremath{pi}}ensuremath{sim}2--4phantom{
ule{0.3em}{0ex}}mathrm{K}$, indicating that the junction becomes a $ensuremath{pi}$ Josephson junction. We find no evidence for second-order Josephson tunneling near ${T}_{ensuremath{pi}}$ in the CPR predicted by several theories.