Magnetic Field Study on the Tc-coupled Spin Excitation in Spin-triplet Superconductor Candidate UTe2

UTe2 has drawn a lot of attention among the superconductivity (SC) community recently for the promising secondary evidence of spin-triplet Cooper pairing shown in this system through temperature-independent NMR Knight shift, the highly anisotropic and unusually large upper critical field, power-law behavior of the specific heat, and ferromagnetic spin fluctuation hinted by the magnetic susceptibility. Inelastic neutron scattering can provide information on the pairing mechanism by probing the low energy excitation due to the ferromagnetic spin fluctuations. Our previous experiments at CNCS on co-aligned UTe2 sample in its 0KL and HK0 plane showed rod-like magnetic excitations at Brillouin zone boundary which develop a spin gap and a spin resonance upon entering the SC state. To further investigate the cause of the spin resonance, we propose to study magnetic field effect on this excitation.