Magnetically-controlled Vortex Dynamics in a Ferromagnetic Superconductor

Abstract

Ferromagnetic superconductors are exceptionally rare because the strong ferromagnetic exchange field usually destroys singlet superconductivity. EuFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$, an iron-based superconductor with a maximum critical temperature of 25 K, uniquely exhibits full coexistence with ferromagnetic order below $T_{\mathrm{FM}}$ $\simeq$ $19$ K. The interplay leads to narrowing of ferromagnetic domains at higher temperatures and spontaneous nucleation of vortices/antivortices at lower temperatures. Here we demonstrate how the underlying magnetic structure controls the superconducting vortex dynamics in applied magnetic fields. Just below $T_{\mathrm{FM}}$ we observe a pronounced peak in the creep activation energy, and magnetic force microscopy measurements reveal the presence of very closely-spaced ($w\ll \lambda$) vortex clusters. We attribute these observations to the formation of vortex polarons for which we present a theoretical description. In contrast, we link strong magnetic irreversibility at low temperatures to a critical current governed by giant flux creep over an activation barrier for vortex-antivortex annihilation near domain walls. Our work suggests new routes for the magnetic enhancement of vortex pinning with important applications in high-current conductors.

13 + 8 pages, 5 + 6 figures

References in corpus (30)

• Depinning and nonequilibrium dynamic phases of particle assemblies driven over random and ordered substrates: a review
• Superconductivity induced by phosphorus doping and its coexistence with ferromagnetism in EuFe${}_2$(As${}_{0.7}$P${}_{0.3}$)${}_2$
• Vortex phase diagram of Ba(Fe0.93Co0.07)2As2 single crystals
• Superconducting materials: Challenges and opportunities for large-scale applications
• Possible re-entrant superconductivity in EuFe2As2 under pressure
• Magnetic structure of EuFe2As2 determined by single crystal neutron diffraction
• Interplay of antiferromagnetism, ferromagnetism and superconductivity in EuFe_2(As_1-xP_x)_2 single crystals
• Superconductivity and Ferromagnetism in Hole-Doped RbEuFe${}_4$As${}_4$
• Coexistence of Superconductivity and Ferromagnetism in P-doped EuFe2As2
• Enhancement of critical current density and vortex activation energy in proton-irradiated Co-doped BaFe2As2
• Charge doping-induced quasiparticle scattering in iron-pnictide superconductors as probed by vortex pinning
• Universal Lower Limit on Vortex Creep in Superconductors
• A New Ferromagnetic Superconductor: CsEuFe${}_4$As${}_4$
• Magnetic ordering and dense Kondo behaviour in EuFe${}_2$P${}_2$
• Superconductivity and ferromagnetism in EuFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$
• Interplay between superconductivity and magnetism in K-doped EuFe2As2
• Magnetic structure of the Eu2+ moments in superconducting EuFe2(As1-xPx)2 with x = 0.19
• Magnetic force sensing using a self-assembled nanowire
• Theory of the magnetic domains phases in ferromagnetic superconductors
• Nanowire magnetic force sensors fabricated by focused electron beam induced deposition
• Ultra-low dissipation patterned silicon nanowire arrays for scanning probe microscopy
• Tailored flux pinning in superconductor/ferromagnet multilayers with engineered magnetic domain morphology from stripes to skyrmions
• Mesoscale phase separation of skyrmion-vortex matter in chiral magnet-superconductor heterostructures
• Size of stripe domains in a superconducting ferromagnet
• Experimental observation of an anomalous peak in isofield M(T) curves in BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$ resembling the fish-tail in $M$($H$) curves further suggesting a possible phase transition in the irreversible regime
• Prediction of polaron-like vortices and dissociation depinning transition in magnetic superconductors: The example of ErNi2B2C
• Complex vortex-antivortex dynamics in the magnetic superconductor EuFe${}_2$(As${}_{0.7}$P${}_{0.3}$)${}_2$
• Imaging magnetic spiral phases, skyrmion clusters, and skyrmion displacements at the surface of bulk Cu${}_2$OSeO${}_3$
• Bulk domain Meissner state in the ferromagnetic superconductor EuFe${}_2$(As${}_{0.8}$P${}_{0.2}$)${}_2$: Consequence of compromise between ferromagnetism and superconductivity
• Polaron-like vortices, dissociation transition and self induced pinning in magnetic superconductors

Cited by in corpus (1)

• Breakdown of the critical state in the ferromagnetic superconductor EuFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$