3:35 PM - NM02.03.05
Late News: Investigating the Impact of Magnetism on Superconductivity in the Magnetic-Superconductor RbEuFe4As4 via Scanning Hall Probe Microscopy
David Collomb1,Simon Bending1,Alexei Koshelev2,Mathew Smylie2,3,Liam Farrar1,Jin Ke Bao2,Duck-Young Chung2,Mercouri Kanatzidis2,4,Wai-Kwong Kwok2,Ulrich Welp2
University of Bath1,Argonne National Laboratory2,Hofstra University3,Northwestern University4
The possible coexistence between magnetism and superconductivity has fascinated scientists ever since the latter’s discovery over 100 years ago. New insights into the interaction between these two forms of order may lead to the realisation of exciting new applications including superconducting spintronics, skyrmionics and fluxonic devices for the next generation of computing hardware. RbEuFe4As4 is a recently-discovered spin-singlet iron-based superconductor with a superconducting transition temperature of Tc = 37K and a magnetic transition temperature of Tm, = 15K, below which both superconductivity and magnetism are present. This large coexistence temperature window makes RbEuFe4As4 an ideal material in which to study the interactions between the two forms of order in detail. Magnetic force microscopy and optical conductivity measurements on RbEuFe4As4 have suggested a weak suppression of superconductivity in the vicinity of Tm , while angle-resolved photoemission spectroscopy measurements indicate a more complete isolation of the two sublattices . Here we use quantitative scanning Hall probe magnetic imaging of superconducting vortices in RbEuFe4As4 to probe changes in key superconducting parameters near the magnetic ordering temperature. Model fits to the vortex profiles as a function of temperature reveal a significant increase in the penetration depth near Tm, followed by a gradual reduction at lower temperatures, revealing that the magnetic ordering leads to a significant reduction in the superfluid density . We corroborate these results with a recently-developed model describing the suppression of superconductivity by correlated magnetic fluctuations . The qualitative agreement between our data and the model suggests that the coupling between the Eu moments and Cooper pairs is weak enough that superconductivity is never destroyed, yet still strong enough to substantially weaken superconductivity. Our results have important implications for understanding coexistence phenomena in other materials systems, which could pave the way to exploiting such materials in future hybrid applications.
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 D. Collomb, S. J. Bending, A. E. Koshelev, M. P. Smylie, L. Farrar, J-K. Bao, D. Y. Chung, M. G. Kanatzidis, W-K. Kwok, and U. Welp. Observing the suppression of superconductivity in RbEuFe4As4 by correlated magnetic fluctuations, arXiv preprint arXiv:2010.09901 (2020).
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