University of Connecticut

Events Calendar

Condensed Matter Physics Seminar

Tuesday, October 8, 2019
2:00pm – 3:00pm

Storrs Campus

Dr. Seok-Woo Lee, Materials Science and Engineering, University of Connecticut

Superelasticity of ThCr2Si2-Structured Intermetallic Compounds at the Micrometer Scale

The work represents a report of the discovery of superelasticity in ThCr2Si2-structured novel intermetallic compound (CaFe2As2) and its hybrid structure (CaKFe4As4) under “uni-axial” compression at the micrometer scale and discusses the strong possibility of deformation-induced superconductivity switching. They exhibit unprecedentedly large elastic limit (10~17%), ultrahigh strength (3~5 GPa), and repeatable cyclic loading response through the reversible lattice collapse caused by making and breaking atomic bonds.1-4 This unique superelasticity mechanism produces a modulus of resilience orders of magnitude higher than that of most engineering materials and enables strain engineering, which refers to the modification of material properties through elastic strain. Our experimental and computational results strongly suggest that superconductivity in a high temperature superconductor, CaKFe4As4, could be turned on/off reliably through this superelasticity process, before fracture occurs, even under “uniaxial” compression. Please note that it is extremely rare to see deformation-induced superconductivity switching under uni-axial deformation, which is the preferred loading mode in engineering applications. Note that our result is only one manifestation of a wider class of such transitions found in over 2500 different ThCr2Si2-structured intermetallic compounds. If we consider their hybrid structure, there could be a much larger number of similar intermetallic compounds. Therefore, our observation can be extended to search for a large group of superelastic and strain-engineerable functional materials, and, more broadly, will lead to various research opportunities in materials science, solid-state physics, superconducting device engineering, and machine-learning-based materials research.

1. J.T. Sypek, C.R. Weinberger, S. Vijayan, M. Aindow, P.C. Canfield, S.-W. Lee, Scripta Mater. 141 10 (2017)

2. J.T. Sypek, H. Yu, K.J. Dusoe, G. Drachuck, H. Petal, A.M. Giroux, A.I. Goldman, A. Kreyssig, P.C. Canfield, S.L. Bud’ko, C.R. Weinberger, S.-W. Lee, Nature Comm. 8 1083 (2017)

3. I.N. Bakst, J.T. Sypek, S.-W. Lee, J.R. Neilson, C.R. Weinberger, – Comp. Mater. Sci. 150, 86 (2018)

4. I.N. Bakst, K.J. Dusoe, G. Drachuk, J.R. Neilson, P.C. Canfield, S.-W. Lee, C.R. Weinberger, Acta Mater. 160 224 (2018)


A. Huang

Physics Department (primary), College of Liberal Arts and Sciences

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