Nat. Mater. https://doi.org/gfs4t8 (2018)

What happens when two types of quantum critical behaviour exist in the same material? This question has been answered by Awadhesh Narayan and collaborators by introducing the concept of multiferroic quantum criticality.

They predicted that europium titanate should exhibit both magnetic and multiferroic quantum critical points, and that alloying with the right amount of barium and strontium would cause the two to be coincident, making the material bicritical. At this point, the scaling behaviour of the magnetic and dielectric susceptibilities should change as the quantum fluctuations associated with one order impacts the other. Also, different forms of superconductivity tend to arise from these ordered phases — s-wave for ferroelectric and d-wave for antiferromagnetic — and investigation of what happens to the pairing in this case is an open direction for future work.