Multiorbital spin-triplet pairing and spin resonance in the heavy-fermion superconductor UTe2

UTe₂ is a candidate spin-triplet superconductor. Among the outstanding issues is the nature of the pairing state. A recent surprising discovery is a resonance in the spin excitation spectrum at an antiferromagnetic (AF) wavevector [1], which stands in apparent contrast to the expected ferromagnetic nature. Here [2], we advanced a theoretical resolution to these seemingly contradictory issues by considering a multiorbital spin-triplet pairing constructed from the dimer of U ions in the unit cell. Because it does not commute with the kinetic part of the Hamiltonian, the pairing function contains both intra- and inter- band terms in the band basis. We demonstrate the existence of a spin resonance at the AF wavevector. Our work illustrates how orbital degrees of freedom can enrich the nature and properties of spin-triplet superconductivity in general.



[1] C. Duan et al., Nature 600, 636 (2021).



[2] L. Chen, H. Hu. C. Lane, E. M. Nica, J.-X. Zhu and Q. Si, "Multiorbital spin-triplet pairing and spin resonance in the heavy-fermion superconductor UTe2”, arXiv:2112.14750.