Abstract
The magnetic and electronic phase diagram of a model for the quasi-one-dimensional alkali-metal iron selenide compound Na2FeSe2 is presented. The novelty of this material is that the valence of iron is Fe2+, contrary to most other iron-chain compounds with valence Fe3+. Using first-principles techniques, we developed a three-orbital tight-binding model that reproduces the ab initio band structure near the Fermi level. Including Hubbard and Hund couplings and studying the model via the density-matrix renormalization group and Lanczos methods, we constructed the ground-state phase diagram. A robust region where the block state ↑↑↓↓↑↑↓↓ is stabilized was unveiled. The analog state in iron ladders, employing 2×2 ferromagnetic blocks, is by now well established, but in chains a block magnetic order has not been observed yet in real materials. The phase diagram also contains a large region of canonical staggered spin order ↑↓↑↓↑↓↑ at very large Hubbard repulsion. At the block-to-staggered transition region, an exotic phase is stabilized with a mixture of both states: an inhomogeneous orbital-selective charge density wave with the exotic spin configuration ↑↑↓↑↓↓↑↓. Our predictions for Na2FeSe2 may guide crystal growers and neutron-scattering experimentalists towards the realization of block states in one-dimensional iron selenide chain materials.
| Original language | English |
|---|---|
| Article number | 035149 |
| Journal | Physical Review B |
| Volume | 102 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jul 15 2020 |
Funding
We thank Yang Zhang for useful discussions. The work of B.P., R.S., N.K., and E.D. was supported by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Materials Sciences and Engineering Division. L.-F.L. was supported by the National Natural Science Foundation of China (Grants No. 11834002 and No. 11674055) and by the China Scholarship Council. G.A. was partially supported by the Center for Nanophase Materials Sciences, which is a U.S. DOE Office of Science User Facility, and by the Scientific Discovery through Advanced Computing (SciDAC) program funded by the U.S. DOE, Office of Science, Advanced Scientific Computing Research and BasicEnergy Sciences, Division of Materials Sciences and Engineering. J.H. acknowledges grant support by the Polish National Agency of Academic Exchange (NAWA) under Contract No. PPN/PPO/2018/1/00035. Validation and some computer runs were conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.