Enhancement of antiferromagnetic spin fluctuations in UTe2 under pressure revealed by Te125 NMR

Devi Vijayan Ambika; Qing-Ping Ding; Corey E. Frank; Sheng Ran; Nicholas P. Butch; Yuji Furukawa

doi:10.1103/4gcm-mbl7

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Enhancement of antiferromagnetic spin fluctuations in UTe2 under pressure revealed by Te125 NMR

Devi Vijayan Ambika, Qing-Ping Ding, Corey E. Frank, Sheng Ran, Nicholas P. Butch, Yuji Furukawa

DOI 10.1103/4gcm-mbl7 · Physical Review B

T1

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Abstract

Characterizing magnetic fluctuations is one of the keys to understanding the origin of superconductivity in the spin-triplet superconductor UTe2, which exhibits two superconducting (SC) phases (SC1 and SC2) under pressure: SC1 where the superconducting transition temperature of Tc decreases with pressure, whereas Tc of SC2 rises with pressure. Previously, D. Ambika et al. [Phys. Rev. B 105, L220403 (2022)] reported the possible coexistence of ferromagnetic (FM) and antiferromagnetic (AFM) spin fluctuations in UTe2 under pressure from their nuclear magnetic resonance (NMR) measurements. To delve into the relationship between the magnetic fluctuations and the two SC phases, we have carried out detailed Te125 NMR measurements on a single crystal of UTe2 with Tc=1.6K at various pressures ranging from 0 to 2.05 GPa. By comparing the temperature T dependence of nuclear spin-lattice relaxation rates divided by temperature 1/T1T with that of the Knight shift K for magnetic fields along the a, b, and c directions, we evidence the enhancement of AFM spin fluctuations with increasing pressure. Based on the results, we suggest that FM spin fluctuations are more favorable for SC1 and AFM spin fluctuations are crucial for SC2. Our findings will inspire further study on this material to understand the peculiar SC phases in detail.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
UTe2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.6	Pressure unresolved	unknown
UTe2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2.8	1.05 GPa	unknown
UTe2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2.1	Pressure not reported	unknown
UTe2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3	1.2 GPa	unknown