Thermodynamic and Magnetic Properties of Heavy Fermion UTe2 Superconductor

Abstract

In the current study, the density of state, condensation energy, specific heat, and magnetization in a spin triplet superconductor UTe₂ have been theoretically investigated. By utilizing the retarded double-time temperature-dependent Green’s function formalism and constructing a model Hamiltonian for the system, we derived expressions for the aforementioned parameters. MATLAB scripts were used to plot the phase diagrams. From the phase diagrams, we observed that the density of state of superconducting electron increases with excitation energy, reaching a maximum at the superconducting gap. Beyond this point, it decreases until it equals the normal state density. Condensation energy decreases with temperature, reaching a minimum at the superconducting transition temperature (T_C). However, it increases with T_C and eventually becomes zero, indicating that the superconducting and normal state energies are equal. Furhermore, specific heat increases with temperature, exhibiting a maximum at T_C followed by a jump, characteristic of a second-order phase transition from the superconducting to the normal state. Both itinerant and localized electron magnetization decrease with temperature, vanishing at T_C = 1.6 K and magnetic phase transition temperature T = 2 K, respectively, signifying a ferromagnetic to paramagnetic transition. Our findings align well with previous research.