"Spin Triplet Superconductivity in UTe2"

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Monday, October 5, 2020 -
1:00pm to 2:00pm
Sheng Ran, Assistant Professor of Physics, Washington University in St. Louis

To view the recorded seminar: "Spin Triplet Superconductivity in UTe2"

Our recent discovery of the novel spin-triplet superconductivity in UTe2 has inspired a lot of interests in the community. Superconducting state of UTe2 closely resembles that of ferromagnetic superconductors, but the normal state is paramagnetic and shows no indication of magnetic ordering. UTe2 exhibits an extremely large, anisotropic upper critical field Hc2, temperature independent NMR Knight shift in the superconducting state, and a large residual normal electronic density of states. All these results strongly indicate that the superconductivity in UTe2 is carried by spin-triplet pairs. Even more striking, superconductivity reenters in the magnetic field of 45 tesla and persists up to 65 tesla, which is the upper limit of magnetic field in our current study. These extreme properties reflect a new kind of exotic superconductivity rooted in magnetic fluctuations and quantum dimensionality. Application of pressure reveals a two-fold enhancement of this unusual superconductivity, which is closely related to the suppression of Kondo coherence. In this talk, I will review our recent results on UTe2.

Sheng Ran’s research aims to realize and understand exotic states of quantum materials, using combined techniques of bulk crystal synthesis, electric and thermal transport measurements under extreme temperature, pressure and magnetic field conditions, and neutron and high energy X-ray scattering.

Discovering pathways to experimentally realize quantum phases of matter and exert control over their properties is one of the central goals of modern physics, which holds promise for a new generation of electronic devices with currently inaccessible and likely unimaginable functionalities. With the explosion in the field of quantum materials in the past decade, it is conceivable that a vast number of new materials with unprecedented quantum states and properties are yet to be discovered. This is exactly what Dr. Ran’s research lab is dedicated to: discovery, synthesis, characterization and control of novel quantum materials with emergent electronic and magnetic states.

Of particular interest are topological quantum materials showing the coexistence of topology and other quantum phases, e.g., superconductivity, magnetism, charge density wave and ferroelectricity. Interplay of topology and these quantum phases gives rise to a variety of exotic quantum states, including the quantum anomalous Hall effect, topological axion states, Majorana fermions, some of which have potential applications for quantum computing and spintronics. Even though topological revolution has been the central theme in condensed matter physics in the past decade, theoretical prediction and experimental realization of such composite topological quantum materials has just started, and extensive experimental efforts to discover and characterize new systems are desperately in need.

 

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