The spin-triplet candidate superconductor UTe­₂ [1] crystallizes in the Immm space group, a = ~4.16 Å, b = ~6.14 Å, and c = ~13.98 Å, and contains three crystallographic sites, one U site which occupies the 4i position and two Te sites, where Te1 occupies the 4j position and Te2 occupies the 4h position [2]. An intrinsic multicomponent superconducting order parameter has been suggested to exist in UTe₂ [3] although contrasting reports indicate that the double superconducting transitions arise due to inhomogeneity within the crystal [4-6]. Recent work has optimized T_c by lowering growth temperatures, reaching the highest reported T_c of 2.0 K. In this talk, I will discuss the evolution of superconducting transition(s) in UTe₂ as a function of annealing via thermodynamic measurements. In addition, detailed single crystal X-ray diffraction studies will highlight crystallographic differences in samples with double or single superconducting transitions to elucidate their origin.

[1] S. Ran et al. Science 365, 684 (2019)

[2] A. J. K. Haneveld et al. J. Less-Common Met. 21, 45 (1970)

[3] I. M. Hayes et al. Science 373, 797 (2021)

[4] L. P. Cairns et al. J. Phys.: Condens. Matter 32, 415602 (2020)

[5] S. M. Thomas et al. arXiv:2103.09194 (2021)

[6] P.F.S. Rosa et al. arXiv:2110.06200 (2021)