Vortex-lattice melting and paramagnetic depairing in the nematic superconductor FeSe

Hardy, F.; Doussoulin, L.; Klein, Thierry; He, Mingquan; Demuer, A.; Willa, Roland; Willa, Kristin; Haghighirad, Amir-Abbas; Wolf, Thomas; Merz, Michael; Meingast, C.; Marcenat, C.

doi:10.1103/physrevresearch.2.033319

Cited by 20 publications

(35 citation statements)

References 111 publications

(166 reference statements)

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“…The specific heat jump µ 0 ∆C/T c = 120 J/m 3 K 2 of WP single crystal has been already measured and reported elsewhere [8], while the slope dH ⊥ c2 /dT| T=T c = −22 mT/K has been obtained by the H ⊥ c2 (T) extracted from the data in the inset of Figure 9 and Γ ≈ 1.4. Thus, we found that G 3D i (0) ≈ 10 −8 , which is very small compared, for instance, with the value ≈10 −2 observed in the iron-selenide superconductor [70], whereas it is comparable to the value observed in the low-temperature superconductor niobium [53,71,72]. As stated before, the Ginzburg number G i measures the strength of thermal fluctuations at the superconducting transition.…”

Section: Resultssupporting

confidence: 62%

Dimensionality of the Superconductivity in the Transition Metal Pnictide WP

et al. 2022

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We report theoretical and experimental results on the transition metal pnictide WP. The theoretical outcomes based on tight-binding calculations and density functional theory indicate that WP is a three-dimensional superconductor with an anisotropic electronic structure and nonsymmorphic symmetries. On the other hand, magnetoresistance experimental data and the analysis of superconducting fluctuations of the conductivity in external magnetic field indicate a weakly anisotropic three-dimensional superconducting phase.

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Section: Resultssupporting

confidence: 62%

Dimensionality of the Superconductivity in the Transition Metal Pnictide WP

et al. 2022

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“…A sharp jump is often smeared out by thermal fluctuations (and inhomogeneity), and consequently, a broad peak appears just below H c c2 . Such a peak structure has been reported above ∼2 K in FeSe [18]. At 1.5 K, although discernible peak structure is not observed, the C(H)/T curve appears to be seriously influenced by the jump anomaly.…”

supporting

confidence: 68%

“…1a and 1b) [6,14,15]. A remarkable feature is the emergence of high-field superconducting phase for both field directions parallel (H ab) [16][17][18] and perpendicular (H c) to the layer [7]. In particular, for H ab, a distinct firstorder phase transition deep inside the superconducting phase, which is revealed by a discontinuous jump of the thermal conductivity, and an anomalous enhancement of the upper critical field H ab c2 have been reported [16].…”

mentioning

confidence: 95%

“…Fermi surface consists of a hole pocket at the zone center and one or two electron pockets at the zone boundary [11,[14][15][16]. A remarkable feature is the emergence of high-field superconducting phases for both H ab [17][18][19] and H c [20]. In particular, for H ab, a distinct first-order phase transition deep inside the superconducting phase, which is revealed by a discontinuous jump of the thermal conductivity, has been reported [17].…”

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confidence: 99%

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Quasiparticle Nodal Plane in the Fulde-Ferrell-Larkin-Ovchinnikov state of FeSe

Kasahara¹,

Suzuki²,

Machida³

et al. 2021

Preprint

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Among exotic pairing states of interacting fermions, the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, characterized by Cooper pairs condensed at finite momentum, has been a long-sought state that remains unresolved in many classes of systems, including superconductors and ultracold atoms. A fascinating aspect of the FFLO state is the emergence of periodic nodal planes in real space, but its observation is still lacking. Here we investigate the order parameter structure for c-axis fields on a high purity single crystal of FeSe. The heat capacity and magnetic torque provide thermodynamic evidence for a distinct superconducting phase at the low-temperature/high-field corner of the phase diagram. Despite the bulk superconductivity, spectroscopic-imaging scanning tunneling microscopy (SI-STM) performed on the same crystal demonstrates that the superconducting order parameter vanishes at the surface upon entering the high-field phase. These results imply that the planar node induced perpendicular to H is pinned at the surface, providing evidence of the FFLO pairing state with zeroth Landau level.

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“…55 Moreover, at sufficiently high temperatures, the vortex state undergoes a melting transition in which pinning becomes ineffective. [56][57][58][59][60] A. Strong pinning theory: predictions for the critical current…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Designing high-performance superconductors with nanoparticle inclusions: comparisons to strong pinning theory

Jones,

Miura,

Yoshida

et al. 2021

Preprint

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One of the most promising routes for achieving unprecedentedly high critical currents in superconductors is to incorporate dispersed, non-superconducting nanoparticles to control the dissipative motion of vortices. However, these inclusions reduce the overall superconducting volume and can strain the interlaying superconducting matrix, which can detrimentally reduce T c . Consequently, an optimal balance must be achieved between the nanoparticle density n p and size d. Determining this balance requires garnering a better understanding of vortex-nanoparticle interactions, described by strong pinning theory. Here, we map the dependence of the critical current on nanoparticle size and density in (Y 0.77 ,Gd 0.23 )Ba 2 Cu 3 O 7−δ films in magnetic fields up to 35 T, and compare the trends to recent results from timedependent Ginzburg-Landau simulations. We identify consistencies between the field-dependent critical current J c (B) and expectations from strong pinning theory. Specifically, we find that that J c ∝ B −α , where α decreases from 0.66 to 0.2 with increasing density of nanoparticles and increases roughly linearly with nanoparticle size d/ξ (normalized to the coherence length). At high fields, the critical current decays faster (∼ B −1 ), suggestive that each nanoparticle has captured a vortex. When nanoparticles capture more than one vortex, a small, high-field peak is expected in J c (B). Due to a spread in defect sizes, this novel peak effect remains unresolved here. Lastly, we reveal that the dependence of the vortex creep rate S on nanoparticle size and density roughly mirrors that of α, and compare our results to low-T nonlinearities in S(T ) that are predicted by strong pinning theory.

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Vortex-lattice melting and paramagnetic depairing in the nematic superconductor FeSe

Cited by 20 publications

References 111 publications

Dimensionality of the Superconductivity in the Transition Metal Pnictide WP

Dimensionality of the Superconductivity in the Transition Metal Pnictide WP

Quasiparticle Nodal Plane in the Fulde-Ferrell-Larkin-Ovchinnikov state of FeSe

Designing high-performance superconductors with nanoparticle inclusions: comparisons to strong pinning theory

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