Signatures of Long-Range Spin-Triplet Component in Andreev Interferometer

Abstract

We analyze the Josephson,$I_{J}$, and dissipative,$I_{V}$, currents in a magnetic Andreev interferometer in the presence of the long-range spin triplet component (LRSTC). Andreev interferometer has a cross-like geometry and consists of a SF$_{l}$ - F - F$_{r}$S circuit and perpendicular to it a N - F - N circuit, where S, F$_{l,r}$ are superconductors and weak ferromagnets with non-collinear magnetisations $\mathbf{M}_{l,r}$, F is a strong ferromagnet with a high exchange energy. The ferromagnetic wire F can be replaced with a non-magnetic wire n. In the limit of a weak proximity effect (PE), we obtain simple analytical expressions for the currents $I_{J}$ and $I_{V}$. In particular, the critical Josephson current in a long Josephson junction (JJ) is $I_{c}(α,β)=I_{0c}χ(α,β)$, where the function $% χ(α,β)$ is a function of angles $(α,β)_{l,r}$ that characterize the orientations of $\mathbf{M}_{l,r}$. The oscillating part of the dissipative current $I_{osc}(V)=χ(α,β)\cos φI_{0}(V)$ in the N - F(n)- N circuit depends on the angles $(α,β)_{l,r}$ in the same way as the critical Josephson current $I_{c}(α,β)$, but can be much greater than the $I_{c}(α,β)$. At some angles the current $I_{c}(α,β)$ changes sign. We briefly discuss a relation between the negative current $I_{c}$ and paramagnetic response. We argue that the measurements of the conductance in N - F(n) - N circuit can be used as another complementary method to identify the LRSTC in S/F heterostructures.