Electronic and magnetic structures that hinder the superconducting state in the collapsed phase of SrCr₂As₂

The lack of superconductivity in the family of materials AB(2)As(2) (A=Sr,Ba and B=Cr,Mn) under doping or pressure is an intriguing issue, considering the resemblance of these materials to their cousin materials and superconductors (Ba,Sr)Fe2As2. In this context, the suppression of magnetism together with the presence of electron and hole pockets in the Brillouin zone seem to be fundamental ingredients to explain superconductivity. In this paper, we report a tetragonal to collapsed-tetragonal phase transition in SrCr2As2 under high pressure with the appearance of hole and electron pockets in the Brillouin zone. In this collapsed-tetragonal phase, a residual local magnetic moment in the Cr-ion site and a finite global magnetic energy are derived. This scenario would suggest why superconductivity is prevented in this compound. Our observations were obtained from the analysis of synchrotron x-ray diffraction measurements of polycrystalline samples of SrCr2As2, and using first-principles simulations, under pressures P in the range 1.4 GPa更多