28 August 2022 to 2 September 2022
Science and Technology Campus, University of Parma
Europe/Rome timezone
Registration and the Call for Abstracts now CLOSED. Paper submission for Conference Proceedings remains open until 5 September

Ubiquitous Spin Freezing in Spin-Triplet Superconductor UTe$_2$

29 Aug 2022, 15:20
20m
Science and Technology Campus, University of Parma

Science and Technology Campus, University of Parma

University of Parma, Italy
Oral Superconductivity Oral contributions

Speaker

Prof. Jeff Sonier (Department of Physics, Simon Fraser University)

Description

The novel superconductor UTe$_2$ is a rare material wherein electrons form Cooper pairs in a unique spin-triplet state with potential topological properties. Theoretically, spin-triplet superconductivity in UTe$_2$ may be explained in terms of pairing mediated by either ferromagnetic or antiferromagnetic fluctuations, but experimentally the magnetic properties of UTe$_2$ remain enigmatic. Here we report on a $\mu$SR study of independently grown UTe$_2$ single crystals that exhibit either a single or double phase transition in the specific heat near the onset of superconductivity. In the absence of an applied magnetic field, we observe an inhomogeneous distribution of magnetic fields in a sizeable volume fraction of all samples studied. The growth in the volume of the magnetic regions is halted by the onset of superconductivity at the critical temperature $T_c$. Upon further cooling, slow fluctuations of the local fields persist until a disordered spin frozen state appears below about one tenth of $T_c$. The $\mu$SR results are consistent with the formation of magnetic clusters in UTe$_2$ due to the influence of disorder on long-range electronic correlations or geometrical magnetic frustration associated with the ladder-like U sublattice structure. Our findings suggest that inhomogeneous magnetic clusters are responsible for the ubiquitous residual linear term and low-temperature upturn in the temperature dependence of the specific heat in UTe$_2$ below $T_c$. The omnipresent magnetic inhomogeneity may also have implications for the interpretation of other low-temperature experimental observations in the superconducting state of UTe$_2$.

Primary author

Prof. Jeff Sonier (Department of Physics, Simon Fraser University)

Co-authors

Dr Sarah Dunsiger (TRIUMF) Dr Shyam Sundar (Department of Physics, Simon Fraser University) Nasrin Azari (Department of Physics, Simon Fraser University) Mariah Goeks (Department of Physics, Simon Fraser University) Dr Shayan Gheidi (Department of Physics, Simon Fraser University) Mae Abedi (Department of Physics, Simon Fraser University) Michael Yakovlev (Department of Physics, Simon Fraser University) John Wilkinson (Clarendon Laboratory, University of Oxford, Department of Physics) Prof. Stephen Blundell (Clarendon Laboratory, University of Oxford, Department of Physics) Dr Shanta Saha (Maryland Quantum Materials Center, Department of Physics, University of Maryland) Prof. Johnpierre Paglione (Maryland Quantum Materials Center, Department of Physics, University of Maryland) Dr Nicholas Butch (NIST Center for Neutron Research, National Institute of Standards and Technology) Dr Priscila Rosa (Los Alamos National Laboratory) Dr Sean Thomas (Los Alamos National Laboratory)

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