Significant enhancement of critical current density in H⁺-intercalated FeSe single crystal

Abstract

Superconducting transition temperature (T c) and critical current density (J c) are two key factors that are not only crucial for probing high temperature superconducting mechanism, but also for practical applications. The simple crystal structure of FeSe is very favorable for the fabrication of thin films and wires, but its application is limited by the relatively low T c and small J c. Previous study has found that the T c of FeSe can be significantly enhanced over 40 K by using protonation method. Here, we present a systematic study of J c and vortex properties of H+-intercalated FeSe (H x -FeSe) single crystals. The value of J c for H x -FeSe single crystal is significantly enhanced, exceeding 1.3×106 A/cm2 at 4 K, which is more than two orders of magnitude larger than 1.1×104 A/cm2 of pristine FeSe. The vortex pinning mechanism of H x -FeSe is found to be surface pinning, which is different from the dominant strong point-like pinning in pristine FeSe. Moreover, the systematic study of the vortex phase transition and the underlying mechanism provides a wealth of information for the vortex phase diagram of H x -FeSe single crystal. Our results confirm that the introduction of H+ intercalations into FeSe not only enhance the T c, but also significantly increase the value of J c, which is favorable for practical applications.

Fabricating Ba0.5Cs0.5Fe2As2 films on BaFe2As2 substrates and their superconducting properties

“…In order to comprehensively understand the pinning mechanism of the vortices, the pinning force density F p ∝ J c H can provide significant information [38,39]. As proposed by Dew-Hughes, there are several pinning mechanisms, such as normal point pinning, and surface pinning.…”

Effect of thickness on the superconducting properties of the thin films of FeTe0.55Se0.45 deposited on YSZ substrates using Pulsed laser deposition (PLD) technique

“…The trend in U H 0 ( ) is similar for both models but the values of U 0 obtained from the modified TAFF model are higher than those estimated using the Arrhenius relation. The magnetic field dependence of the TAE can be used to distinguish between a 2D or 3D formation of vortex lattice [29][30][31]. U 0 versus H plots show logarithmic dependence of TAE, Ũ H ln 0 ( ) and power law µ a -U H H 0 ( ) (where a is the scaling parameter).…”

“…The thermally activated flux flow (TAFF) model can be used to visualize the vortex physics of IBSs, which is remarkably similar to cuprate superconductors [28]. An interesting property of IBSs and cuprates is the change in dimensionality of the vortex matter in the applied magnetic field [29][30][31]. They can either show 2D or 3D vortex lattice behaviour.…”

“…They can either show 2D or 3D vortex lattice behaviour. The magnetic field dependence of the TAE (U 0 ) has been used to differentiate between 2D or 3D behaviour of the vortex lattice [31]. Several researchers have examined the vortex phase diagram of IBSs to better understand the significant magnetotransport features for technological applications [25,28,32].…”

Review of Single Crystal Synthesis of 11 Iron-Based Superconductors

“…Under high pressure, the T c of FeSe can be elevated to approximately 38 K, and a new magnetic order emerges within a specific pressure range once the nematic phase is suppressed [16][17][18][19]. Chemical methods, such as intercalation [20,21], ionic liquid gating [22][23][24] and potassium deposition [25,26], have been employed to raise the T c to over 40 K. Remarkably, monolayer FeSe films on doped SrTiO 3 substrates have exhibited superconductivity with the T c surpassing 65 K [27,28]. These materials offer various pathways to achieve a high T c and exhibit unconventional superconducting behavior.…”