Boosting the superconducting properties of Fe(Se, Te) through hexagonal phase manipulation

Improving Superconducting Performance of Fe(Se, Te) with In Situ Formed Grain-Boundary Strengthening and Flux Pinning Centers

“…Recently, more and more iron-based superconductor (IBS)-related research has focused on Fe­(Se, Te) superconductors because of their simple lattice harmonicity and nontoxic chemical nature. − The critical temperature ( T c ) of pristine Fe­(Se, Te) is ∼15 K, which is suitable for application under liquid helium. Meanwhile, the T c value of the Fe­(Se, Te) system is sensitive to both the chemical composition and dimensions so that it can be tuned within a wide range from 15 to 65 K with doping, pressure, annealing, and fabrication of films or even monolayer ultra-thin Fe­(Se, Te) films to cater for higher working temperatures. − On the other hand, the obtained high critical current density ( J c ) in Fe­(Se, Te)-coated conductors of ∼10 6 A/cm 2 at self-field and ∼10 5 A/cm 2 at 30 T is desirable for working in an ultrahigh magnetic field. , The upper critical field ( H c2 ), reported to be above 45 T, makes Fe­(Se, Te) adequate for working under the magnetic flux density B > 15 T condition at 4.2 K. , Hence, Fe­(Se, Te)-based superconductors are now considered to be candidates for replacing the conventional low-temperature superconductors, such as NbTi and Nb 3 Sn. , …”

“…10,11 The upper critical field (H c2 ), reported to be above 45 T, makes Fe(Se, Te) adequate for working under the magnetic flux density B > 15 T condition at 4.2 K. 12,13 Hence, Fe(Se, Te)-based superconductors are now considered to be candidates for replacing the conventional low-temperature superconductors, such as NbTi and Nb 3 Sn. 14,15 Despite their decent properties, there is still a long way to go for large-scale application of Fe(Se, Te) superconductors due to the very low J c in Fe(Se, Te) wires and tapes. 16 Currently, the J c values of reported Fe(Se, Te) wires or tapes fabricated by the traditional powder-in-tube process are only around 10 3 A/cm 2 , which are significantly lower than those of Fe(Se, Te) single crystals or films (∼10 5 A/cm 2 ).…”

Fe(Se,Te) from melting routes: the influence of thermal processing on microstructure and superconducting properties

“…A high temperature (680 • C) annealing does not lead to their disappearance, suggesting these phases are stable at the annealing temperature [12]. The nature, morphology and structure of the secondary phases is been reported however to be dependent on the annealing temperature [13,14] and more recently on the material composition [15], indicating that different conditions lead to different materials and therefore that the system phase composition and morphology is highly dependent on its thermal history.…”