Amazing stuff!
"... in a few unconventional materials, competition between ferromagnetic ordering, where the magnetic moments align to point in the same direction, and superconducting ordering, where paired electron moments point in opposite directions, can lead to a phenomenon known as re-entrant superconductivity (RSC). This is where, in an applied field, the magnetic ordering will at first destroy superconductivity, but when the field increases further, the superconductivity reappears. ...
now observed this phenomenon for the first time in a two-dimensional (2D) unconventional superconductor. ...
RSC has previously been observed in three-dimensional ferromagnetic materials such as CeRh2As2, organic superconductors and possibly in so-called heavy fermion compounds such as UTe2. ..."
From the abstract:
"A magnetic field typically suppresses superconductivity by either breaking Cooper pairs via the Zeeman effect or inducing vortex formation.
However, under certain circumstances, a magnetic field can stabilize superconductivity instead.
This seemingly counterintuitive phenomenon is associated with magnetic interactions and has been extensively studied in three-dimensional materials.
By contrast, this phenomenon, hinting at unconventional superconductivity, remains largely unexplored in two-dimensional systems, with moiré-patterned graphene being the only known example.
Here, we report the observation of reentrant superconductivity at the epitaxial (110)-oriented LaTiO3-KTaO3 interface. This phenomenon occurs across a wide range of charge carrier densities, which, unlike in three-dimensional materials, can be tuned in situ via electrostatic gating.
We propose that the observed reentrant superconductivity can arise from an interplay between strong spin-orbit coupling and a magnetic field–driven modification of the Fermi surface.
Our findings provide insight into reentrant superconductivity and establish a robust platform for exploring unconventional superconducting phenomena in two-dimensional systems."
A magnetic field that kills superconductivity can also bring it back (original news release) "Magnetic fields are generally known to destroy superconductivity in a material. However, in exceptional cases they can lead to what is known as “reentrant superconductivity”— where superconductivity disappears as expected but then unexpectedly returns when the magnetic field is increased further. This behavior is sometimes seen in bulk, three-dimensional materials, but now, in a study published in Science Advances, a team led by the RIKEN Center for Emergent Matter Science (CEMS) in Japan has seen the phenomenon in a very thin conducting layer at the boundary between two insulating oxide materials. Because oxide interfaces can be precisely engineered and controlled, the discovery provides a new platform for investigating unconventional forms of superconductivity and the quantum mechanisms that allow it to survive under unusual conditions."
Reentrant superconductivity at an oxide heterointerface (open access)
Yes, no, yes: Schematic showing how an applied field affects superconductivity in a LaTiO3/KTaO3 heterostructure.
Fig. 1. Properties of the (110)-oriented LaTiO3-KTaO3 interface.
Fig. 2. Experimental visualization of reentrant superconducting response.
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