Deposition and properties of Fe(Se,Te) thin films on vicinal CaF₂substrates

Abstract

We report on the growth of epitaxial Fe 1+δ Se 0.5 Te 0.5 thin films on 0°, 5°, 10°, 15°and 20°v icinal cut CaF 2 single crystals by pulsed laser deposition. In situ electron and ex situ x-ray diffraction studies reveal a tilted growth of the Fe 1+δ Se 0.5 Te 0.5 films, whereby under optimized deposition conditions the c-axis alignment coincides with the substrate [001] tilted axis up to a vicinal angle of 10°. Atomic force microscopy shows a flat island growth for all films. From resistivity measurements in longitudinal and transversal directions, the ab-and c-axis components of resistivity are derived and the mass anisotropy parameter is determined. Analysis of the critical current density indicates that no effective c-axis correlated defects are generated by vicinal growth, and pinning by normal point core defects dominates. However, for H||ab the effective pinning centers change from surface defects to point core defects near the superconducting transition due to the vicinal cut. Furthermore, we show in angular-dependent critical current density data a shift of the ab-planes maxima position with the magnetic field strength.

Thickness-induced crossover from strong to weak collective pinning in exfoliated FeTe$_{0.6}$Se$_{0.4}$ thin films at 1 T

“…This clearly shows that J c depends only on the perpendicular component of the magnetic field. Such magnetic field and angle dependences of J c are consistent with previous works on FTS thin films [13][14][15][16]. Now we move on to the d dependence of J c .…”

“…Among all kinds of IBSs, the iron-based chalcogenide FeTe 1−x Se x with x = 0.4 ∼ 0.5 (FTS) has the simplest crystal structure with only FeCh (Ch = Se or Te) layers. There have been many reports on bulk [3][4][5][6][7][8][9][10][11][12] and thinfilm [13][14][15][16] FTS single crystals, which enable a detailed discussion of the pinning mechanism. Although the critical temperature T c is not so high, the upper critical field is comparable to other IBSs.…”

Anisotropy of the transport properties of NdFeAs(O,F) thin films grown on vicinal substrates

“…Here, we report on the transport properties of NdFeAs(O,F) thin films with dif-ferent F-doping levels grown on vicinal substrates for which the [001] direction is 5 • or 10 • tilted toward the [100] direction. Using these off-axis grown thin films, we evaluate the resistivity anisotropy, adopting the method that has been employed to study the anisotropy of Bi 2 Sr 2 CaCu 2 O 8 15 , YBa 2 Cu 3 O 7 (YBCO) [16][17][18] , MgB 2 19 and Fe(Se,Te) 20 .…”

Anisotropy of the In-Plane and Out-of-Plane Resistivity and the Hall Effect in the Normal State of Vicinal-Grown YBa2Cu3O7−δ Thin Films

“…The anisotropic resistivities of several HTSCs thin films, grown on vicinal substrates, have been studied. Among them are optimally doped [ 6 ] and oxygen deficient YBCO [ 16 ], Bi Sr CaCu O [ 17 ], Hg Re Ba CaCu O [ 18 ], and, recently, the iron-based superconductors Fe Se Te [ 19 ] and NdFeAs(O,F) [ 20 ].…”