Low-temperature Magnetic Fluctuations Investigated by ${}^{125}$Te-NMR on the Uranium-based Superconductor UTe${}_2$

Abstract

To investigate the static and dynamic magnetic properties on the uranium-based superconductor UTe${}_2$, we measured the NMR Knight shift $K$ and the nuclear spin-lattice relaxation rate $1/T_1$ in $H\parallel a$ by ${}^{125}$Te-NMR on a ${}^{125}$Te-enriched single-crystal sample. $1/T_{1}T$ in $H\parallel a$ is much smaller than $1/T_{1}T$ in $H\parallel b$ and $c$, and magnetic fluctuations along each axis are derived from the $1/T_{1}T$ measured in $H$ parallel to all three crystalline axes. The magnetic fluctuations are almost identical at two Te sites and isotropic at high temperatures, but become anisotropic below 40 K, where heavy-fermion state is formed. The character of magnetic fluctuations in UTe${}_2$ is discussed with the comparison to its static susceptibility and the results on other U-based superconductors. It is considered that the magnetic fluctuations probed with the NMR measurements are determined by the magnetic properties inside the two-leg ladder formed by U atoms, which are dominated by the $q_a$ = 0 ferromagnetic fluctuations.

10 pages, 6 figures,

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Cited by in corpus (8)

• Absence of Spontaneous Magnetic Fields Due to Time-Reversal Symmetry Breaking in Bulk Superconducting UTe2
• Longitudinal spin fluctuations driving field-reinforced superconductivity in UTe${}_2$
• Clear Reduction in Spin Susceptibility and Superconducting Spin Rotation for $H\parallel a$ in the Early-Stage Sample of Spin-Triplet Superconductor UTe${}_2$
• Reinforcement of superconductivity by quantum critical fluctuations of metamagnetism in UTe${}_2$
• Intrinsic low-temperature magnetic properties on the ultra-clean UTe${}_2$ with $T_{\mathrm{c}}$ = 2.1 K revealed by ${}^{125}$Te NMR
• Dramatic elastic response at the critical end point in UTe${}_2$
• $b$-axis and $c$-axis Knight shift measurements in the superconducting state on ultraclean UTe${}_2$ with $T_c$ = 2.1 K
• Boosted magnetic fluctuations at the onset of superconductivity in UTe${}_2$ beyond 40 T