Long-range superharmonic Josephson current and spin-triplet pairing correlations in a junction with ferromagnetic bilayers

The long-range spin-triplet supercurrent transport is an interesting phenomenon in the superconductor/ferromagnet ([inline-graphic not available: see fulltext]) heterostructure containing noncollinear magnetic domains. Here we study the long-range superharmonic Josephson current in asymmetric [inline-graphic not available: see fulltext] junctions. It is demonstrated that this current is induced by spin-triplet pairs [inline-graphic not available: see fulltext] − [inline-graphic not available: see fulltext] or [inline-graphic not available: see fulltext] + [inline-graphic not available: see fulltext] in the thick [inline-graphic not available: see fulltext] layer. The magnetic rotation of the particularly thin [inline-graphic not available: see fulltext] layer will not only modulate the amplitude of the superharmonic current but also realise the conversion between [inline-graphic not available: see fulltext] − [inline-graphic not available: see fulltext] and [inline-graphic not available: see fulltext] + [inline-graphic not available: see fulltext]. Moreover, the critical current shows an oscillatory dependence on thickness and exchange field in the [inline-graphic not available: see fulltext] layer. These effect can be used for engineering cryoelectronic devices manipulating the superharmonic current. In contrast, the critical current declines monotonically with increasing exchange field of the [inline-graphic not available: see fulltext] layer and if the [inline-graphic not available: see fulltext] layer is converted into half-metal, the long-range supercurrent is prohibited but [inline-graphic not available: see fulltext] still exists within the entire [inline-graphic not available: see fulltext] region. This phenomenon contradicts the conventional wisdom and indicates the occurrence of spin and charge separation in present junction, which could lead to useful spintronics devices.