Vortex glass-liquid transition and activated flux motion in an epitaxial, superconducting NdFeAs(O,F) thin film

Abstract

An epitaxial NdFeAs(O,F) thin film of 90 nm thickness grown by molecular beam epitaxy on MgO single crystal with T c = 44.2 K has been investigated regarding a possible vortex glass-liquid transition. The voltage-current characteristics show excellent scalability according to the vortexglass model with a static critical exponent ν of around 1.35 and a temperature-dependent dynamic exponent z increasing from 7.8 to 9.0 for the investigated temperature range. The large and non-constant z values are discussed in the frame of 3D vortex glass, thermally activated flux motion, and inhomogeneity broadening.

Microscopic origin of highly enhanced current carrying capabilities of thin NdFeAs(O,F) films

“…At lower fields, the data differ from these functions because of the crossover to the regime of single vortex pinning, where U 0 is constant. The value of this cross-over field to single vortex pinning of ∼2–3 T is comparable to literature data on Nd1111, La1111, and Sm1111 ( ref. 38 and references therein).…”

“…The value of this cross-over eld to single vortex pinning of $2-3 T is comparable to literature data on Nd1111, La1111, and Sm1111 (ref. 38 and references therein). Critical current density.…”

Vortex state study of superconducting Fe(Te, Se) thin films deposited on SrTiO3 substrate by pulsed laser deposition technique

“…4(c, d) and found similar to 122-type K 0.78 Fe 1.70 Se 2 single crystals. 21 The VG to VL transitions are similar to the results of Hänisch et al 23 On comparing the VL regions of thin films S1 to that of S2, we see that the VL region of S2 is found at high temperature which suggests better superconducting properties of S2. Also, the transition from the unpinning VL to pinned VL is found high for S2 thin films.…”

Transport characterization and pinning analysis of BaFe1.9Ni0.1As2.05 thin films

“…For example, T g ∼14.2 K for H//c at 10 T in [5], T g ∼17.5 K for H//c at 3 T in [35], while the T g values in our thin films for H//c at 3 and 9 T are 14.6 and 11.2 K, respectively. Larger critical exponents in thin films than single crystals are also observed in cuprate thin films, such as YBa 2 Cu 3 O 7−δ [36] and Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ thin films [37], and IBS thin films, such as NdFeAs(O,F) thin films [16]. The larger critical exponents in thin films than single crystals may be related to the inherent disorder of thin films, for various defects can be easily introduced during film growth.…”

“…Despite of their intermediate superconducting transition temperature T c , the IBSs are advantageous in terms of critical grain boundary robust, lower anisotropy, higher crystallographic symmetry and production cost. Among IBSs, VG phase transition was also reported in Co, Ni, K and P doped BaFe 2 As 2 (Ba122) single crystals [5][6][7][8][9][10][11][12], 11 single crystals [13], and 11 111 single crystals [14], polycrystals [15] and thin films [16]. However, there is an inconsistence among the experimental data of the same IBS system from different groups, which may be caused by the variety of the studied samples.…”