Magnetic entropy of UTe2

Recently rediscovered orthorhombic compound UTe$_{2}$ exhibits superconductivity at low temperatures below 2 K. The origin of superconductivity is still unknown even though its properties were investigated by different techniques and reported in literature [1,2]. One possibility to uncover the origin of superconductivity is to investigating physical properties at temperatures above superconducting transition as it is most likely connected to magnetic properties. Existence of ferromagnetic fluctuations along the a-axis was suggested based on microscopic, thermodynamic and transport measurements [1,3], while antiferromagnetic fluctuations were found by inelastic neutron scattering along the b-axis [4].
We investigate magnetic properties for all crystallographic axes in fields up to 7 T and temperature interval from 2 K up to 60 K. The obtained data are than evaluated by Maxwell relations between entropy and magnetization to obtain the change of magnetic part of entropy in T-H diagram. The entropy for field along the a-axis show ferromagnetic-like behavior with unusual behavior below ~ 7 K, while for field along the b-axis we observe antiferromagnetic-like behavior. The obtained results are discussed together with published results.

[1] C. Duan, K. Sasmal, M.B. Maple, A. Podlesnyak, J.X. Zhu, Q. Si, P. Dai, Incommensurate Spin Fluctuations in the Spin-Triplet Superconductor Candidate UTe$_{2}$, Phys. Rev. Lett. 125, 237003 (2020).
[2] D. Aoki, F. Honda, G. Knebel, D. Braithwaite, A. Nakamura, D.X. Li, Y. Homma, Y. Shimizu, Y.J. Sato, J.P. Brison, J. Flouquet, Multiple superconducting phases and unusual enhancement of the upper critical field in UTe$_{2}$, J. Phys. Soc. Japan. 89, 053705 (2020).
[3] K. Willa, F. Hardy, D. Aoki, D. Li, P. Wiecki, G. Lapertot, C. Meingast, Thermodynamic signatures of short-range magnetic correlations in UTe$_{2}$, arXiv: 2107.02706 (2021).
[4] W. Knafo, G. Knebel, P. Steffens, K. Kaneko, A. Rosuel, J.-P. Brison, J. Flouquet, D. Aoki, G. Lapertot, S. Raymond, Low-dimensional antiferromagnetic fluctuations in the heavy-fermion paramagnetic ladder UTe$_{2}$, arXiv2107.02706 (2021).