First-principles prediction of spin-density-reflection symmetry driven magnetic transition of CsCl-type FeSe

• Published in: arXiv.org
• Main Authors: Rahman, Gul, In Gee Kim, Freeman, Arthur J
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 13.07.2010
• Subjects: Antiferromagnetism; Approximation; Density functional theory; Ferromagnetic materials; First principles; Lattice parameters; Magnetic materials; Magnetic moments; Magnetic transitions; Magnetism; Mathematical analysis; Orbital stability; Phase transitions; Physics - Materials Science; Reflection; Spin-orbit interactions; Symmetry
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1005.5112

Based on results of density functional theory (DFT) calculations with the local spin density approximation (LSDA) and the generalized gradient approximation (GGA), we propose a new magnetic material, CsCl-type FeSe. The calculations reveal the existence of ferromagnetic (FM) and antiferromagnetic (AFM) states over a wide range of lattice constants. At 3.12\,Å in the GGA, the equilibrium state is found to be AFM with a local Fe magnetic moment of \(\pm 2.69\,\mu_\mathrm{B}\). A metastable FM state with Fe and Se local magnetic moments of \(2.00\,\mu_\mathrm{B}\) and \(-0.032\,\mu_\mathrm{B}\), respectively, lies 171.7\,{meV} above the AFM state. Its equilibrium lattice constant is \(\sim 2\)\,{\%} smaller than that of the AFM state, implying that when the system undergoes a phase transition from the AFM state to the FM one, the transition is accompanied by volume contraction. Such an AFM-FM transition is attributed to spin-density \(z\)-reflection symmetry; the symmetry driven AFM-FM transition is not altered by spin-orbit coupling. The relative stability of different magnetic phases is discussed in terms of the local density of states. We find that CsCl-type FeSe is mechanically stable, but the magnetic states are expected to be brittle.