In-plane uniaxial stress effects on the structural and electronic properties of BaFe2As2 and CaFe2As2

Article

关键词: IRON ARSENIDE SUPERCONDUCTOR;    TOTAL-ENERGY CALCULATIONS;    AUGMENTED-WAVE METHOD;    BASIS-SET;    DYNAMICS;    METALS;   

DOI  :  10.1103/PhysRevB.87.174503

来源: SCIE

【 摘 要 】

Starting from the orthorhombic magnetically ordered phase, we investigate the effects of uniaxial tensile and compressive stresses along a, b, and the diagonal a + b directions in BaFe2As2 and CaFe2As2 in the framework of ab initio density functional theory (DFT) and a phenomonological Ginzburg-Landau model. While-contrary to the application of hydrostatic or c-axis uniaxial pressure-both systems remain in the orthorhombic phase with a pressure-dependent nonzero magnetic moment, we observe a sign-changing jump in the orthorhombicity at a critical uniaxial pressure, accompanied by a reversal of the orbital occupancy and a switch between the ferromagnetic and antiferromagnetic directions. Our Ginzburg-Landau analysis reveals that this behavior is a direct consequence of the competition between the intrinsic magneto-elastic coupling of the system and the applied compressive stress, which helps the system to overcome the energy barrier between the two possible magneto-elastic ground states. Our results shed light on the mechanisms involved in the detwinning process of an orthorhombic iron-pnictide crystal and on the changes in the magnetic properties of a system under uniaxial stress.

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