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 ([Image: see text]) heterostructure containing noncollinear magnetic domains. Here we study the long-range superharmonic Josephson current in asymmetric [Image: see text] junctions. It is demonstrated that this current is induced by spin-triplet pairs [Image: see text] − [Image: see text] or [Image: see text] + [Image: see text] in the thick [Image: see text] layer. The magnetic rotation of the particularly thin [Image: see text] layer will not only modulate the amplitude of the superharmonic current but also realise the conversion between [Image: see text] − [Image: see text] and [Image: see text] + [Image: see text]. Moreover, the critical current shows an oscillatory dependence on thickness and exchange field in the [Image: see text] 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 [Image: see text] layer, and if the [Image: see text] layer is converted into half-metal, the long-range supercurrent is prohibited but [Image: see text] still exists within the entire [Image: see text] 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.