Evidence for a pressure-induced antiferromagnetic quantum critical point in intermediate-valence UTe2

Author(s)

Thomas, S. M. ; Santos, F. B. ; Christensen, M. H. ; Asaba, T. ; Ronning, F. ; Thompson, J. D. ; Bauer, E. D. ; Fernandes, R. M. ; Fabbris, G. ; Rosa, P. F. S.

• Document type: Journal article
• Source: SCIENCE ADVANCES; v. 6, n. 42, p. 7-pg., 2020-10-01.

Abstract

UTe2 is a recently discovered unconventional superconductor that has attracted much interest because of its potentially spin-triplet topological superconductivity. Our ac calorimetry, electrical resistivity, and x-ray absorption study of UTe2 under applied pressure reveals key insights on the superconducting and magnetic states surrounding pressure-induced quantum criticality at P-c1 = 1.3 GPa. First, our specific heat data at low pressures, combined with a phenomenological model, show that pressure alters the balance between two closely competing superconducting orders. Second, near 1.5 GPa, we detect two bulk transitions that trigger changes in the resistivity, which are consistent with antiferromagnetic order, rather than ferromagnetism. Third, the emergence of magnet-ism is accompanied by an increase in valence toward a U4+ (5f(2)) state, which indicates that UTe2 exhibits intermediate valence at ambient pressure. Our results suggest that antiferromagnetic fluctuations may play a more substantial role on the superconducting state of UTe2 than previously thought. (AU)

• FAPESP's process: 18/20546-1 - Single crystal growth of (Hf, Sc, RE)V2Ga4 (RE = rare earth) and (Fe, Co, Ru)1-xRMxGa3 (RM = refractory metals) compounds and the study of their Fermi surface, electronic structure, and superconducting properties under extreme conditions
• Grantee: Frederico Benedetto Santos
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• FAPESP's process: 16/11565-7 - Investigation of the superconductivity and magnetism in compounds that crystallize on the YbMo2Al4 and IrIn3 prototype
• Grantee: Frederico Benedetto Santos
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)