SPICE Workshop on Unconventional Superconductors and Magnets May 12th - 14th, 2026
Raquel Queiro
In unconventional superconductors, electrons can mitigate strong electronic repulsion by pairing with finite angular momentum, leaving behind nodal quasiparticles that coexist with the condensate. Gap nodes are among the clearest signatures of unconventional superconductivity, but establishing them unambiguously remains challenging in low-Tc materials. In this talk I will discuss recent theoretical and experimental progress on transition metal dichalcogenide Td-MoTe2, a superconducting Weyl semimetal, and show how nodal quasiparticles themselves can be turned into a precise diagnostic of pairing symmetry. High-Q microwave resonators reveal lambda ~ T^2 scaling of the penetration depth at low temperature together with an anomalous nonlinear Meissner effect lambda ~ |I| in an applied current I, providing complementary signatures of nodal quasiparticles in the superfluid response. A complementary microwave pump–probe technique further uncovers quasiparticle recombination dynamics -- the relaxation of broken Cooper pairs back into the ground state -- displaying power-law scaling of the recombination lifetime across multiple devices, consistent with nodal excitations coupled to acoustic phonons. Taken together, these equilibrium and nonequilibrium responses provide strong evidence for nodal superconductivity in MoTe2 and show how nonlinear electrodynamics and relaxation dynamics can serve as sharp probes of unconventional pairing.