Quasi-2D surface behavior at the surface of aged β-FeSe single crystals

LANOËL, L; ROZAS, G.; BRUCHHAUSEN, A.; AMIGÓ, M L; ALE CRIVILLERO, M. V.; HOFER, A.; VILLAFUERTE, M.; BRIDOUX, G.; NIEVA, G.

Congreso; APS March Meeting; 2022

American Physical Association

We performed a thorough study of the origin and properties of aging in the surface of single crystals of the β-FeSe superconductor. Studying this material by Raman spectroscopy, in backscattering geometry along the c-axis, we observed a new (not expected for this configuration) vibrational mode. To determine this new mode origin, we performed Raman measurements in a wide range of temperature (5 - 800 K, see accompanying video), X-Ray Photoelectron spectroscopy (XPS) on fresh and aged samples, and electrical transport measurements. Based on the experimental results, anda simple bidimensional model, we propose that aging could produce chemical pressure, or a descorrelation of the first sheets of the sample, resulting in a enhancement of the superconducting properties of the material.