Novel Magnetoelectric Effects in Gyrotropic Superconductors and a Case Study of Transition Metal Dichalcodenides

In this work, we classify superconductors according to their magnetoelectric response. Among all the noncentrosymmetric superconductors, only superconductors with gyrotropic point groups have non-zero magnetoelectric response such that a supercurrent can induce a nite spin magnetization. We call these superconductors gyrotropic superconductors. Importantly, the general form of the magnetoelectric response is dictated by the point group symmetry and lead to novel magnetoelectric effects. Novel magnetoelectric effects of several noncentrosymmetric superconductors, including superconductors with chiral lattice symmetry and atomically thin superconducting transition metal dichalcogenides are discussed. Using a newly discovered monolayer 2H-structure NbSe2 as an example, we further show that how an unconventional magnetoelectric response can be induced by strain in superconductors with non-gyrotropic point groups.