Method for reliable realization of a varphi Josephson junction

We propose a method to realize a $\phi$ Josephson junction by combining alternating 0 and $\pi$ parts (sub junctions) with an intrinsically non-sinusoidal current-phase relation (CPR). Conditions for the realization of the $\phi$ ground state are analyzed. It is shown that taking into account the non-sinusoidal CPR for a "clean junction with a ferromagnetic (F) barrier, one can significantly enlarge the domain (regime of suitable F-layer thicknesses) of the $\phi$ ground state and make the practical realization of $\phi$ Josephson junctions feasible. Such junctions may also have two different stable solutions, such as 0 and $\pi$, 0 and $\phi$, or $\phi$ and $\pi$

Visualization of ferromagnetic domains in ErNi(2)B(2)C single crystals: Weak ferromagnetism and its coexistence with superconductivity

The magnetic flux structure in the basal plane, (001), of single crystals of superconducting ErNi(2)B(2)C was studied by high resolution Bitter decoration at temperatures below T(c) (superconducting transition) and/or T(N) (antiferromagnetic transition). Two sets of domain boundaries, in {110} and {100} planes, were observed. The temperature range in which the {100} domain boundaries were observed coincides with the weak ferromagnetic (WFM) ordering in this material. On the other hand, the {110} twin boundaries-the antiferromagnetic domain boundaries-were observed below T(N). For comparison, TbNi(2)B(2)C, the related compound with higher magnetic ordering temperatures but no superconductivity, was also studied. The possibility of interpretation of {100} boundaries as Bloch domain walls in the weakly ferromagnetic phase, for T < T(WFM)< T(N) (TbNi(2)B(2)C) or T < T(WFM)< T(N)< T(c) (ErNi(2)B(2)C), is discussed.This article is published as Veschunov, I. S., L. Ya Vinnikov, S. L. Bud’ko, and P. C. Canfield. "Visualization of ferromagnetic domains in Er Ni 2 B 2 C single crystals: Weak ferromagnetism and its coexistence with superconductivity." Physical Review B 76, no. 17 (2007): 174506. DOI: 10.1103/PhysRevB.76.174506. Copyright 2007 American Physical Society. Posted with permission

Magnetic moment manipulation by triplet Josephson current

The induced magnetic moment, provided by the bands electrons, is calculated in a variety of Josephson junctions with multilayered ferromagnetic (F) weak link. The noncollinear magnetization of the F layers provides the conditions necessary to generate triplet superconducting correlations. It leads to the long-range induced magnetic moment, emerging in the superconducting (S) layers. It is shown to be dependent on the Josephson phase. By tuning the Josephson current, one may control the long-range induced magnetic moment. Alternatively, applying the voltage we can generate an oscillatory magnetic moment. The detection of such a spin effect may serve as independent evidence of the triplet superconductivity. The proposed mechanism seems to be attractive for superconducting spintronic devices with low dissipation