Gaia Grimaldi1,Antonio Leo2,1,Masood Khan2,1,Angela Nigro2,1,Andrea Augieri3,Mario Scuderi1,Valeria Braccini1,Marina Putti4
CNR1,University of Salerno2,ENEA3,University of Genova4
Gaia Grimaldi1,Antonio Leo2,1,Masood Khan2,1,Angela Nigro2,1,Andrea Augieri3,Mario Scuderi1,Valeria Braccini1,Marina Putti4
CNR1,University of Salerno2,ENEA3,University of Genova4
A challenging material for high magnetic field applications has to face a high current-carrying capability as well as a very low anisotropy. So far this was a motivation in favor of YBCO that is known as a 3D superconductor with a γ factor lower than 10 and critical current density above some MA/cm<sup>2</sup>. The race of Iron-Based Superconductors is driven by anisotropy, dimensionality and material defects acting as pinning centers. Our experience tells us that the Fe(Se,Te) chalcogenide superconductor can compete with High Temperature Superconductors due to its rather simple crystal structure, huge upper critical fields with respect to LTS, lower anisotropy compared to HTS. By the way, the vortex physics in the mixed state of this compound is rich of phenomena [1], with a surprising anisotropy in the flux pinning energy [2] and the observation of Flux Flow Instability induced by an electronic mechanism at very high bias currents [3,4]. We also present a pioneering behavior of the upper critical field that is accounted for by Pauli paramagnetic and orbital pair-breaking effects with a non-zero spin-orbit coupling emerging from the angular dependence of the H-T phase diagram. Beyond the very low anisotropy of Fe(Se,Te) superconductor and its multiband nature, the additional degree of freedom in our angular measurements shows emerging anisotropic trends of flux pinning energy <i>U<sub>0</sub></i>(H,T,θ), irreversibility field <i>H<sub>irr</sub></i>(H,T,θ) and critical current density <i>J<sub>c</sub></i>(H,T,θ) as well. A deep investigation of Fe(Se,Te) microstructure at nanoscale reveals indeed extended defects elongated preferentially parallel to<i> ab</i> plane [5], thus mimicking the layered anisotropy usually observed in YBCO. Nevertheless, by looking at anisotropy, dimensionality and pinning, Fe(Se,Te) films grown on CaF<sub>2</sub> substrate are able to struggle against YBCO films, particularly at high magnetic fields, those relevant for practical applications.<br/>[1] A. Galluzzi et al., Sci. Rep. 11, 7247 (2021)<br/>[2] M. R. Khan et al., Materials 14, 5289 (2021)<br/>[3] G. Grimaldi et al., Sci. Rep. 8, 4150 (2018)<br/>[4] A. Leo et al., Supercond. Sci. Technol. 33, 104005 (2020)<br/>[5] M. Scuderi et al., Sci. Rep. 11, 20100 (2021)<br/>Acknowledgments<br/>Work partially supported by MIUR-PRIN project "HiBiSCUS" - grant no. 201785KWLE and PON Research and Competitiveness 2007-2013 under grant agreement PON NAFASSY, PONa3_00007