Orbital-selective Peierls phase in the metallic dimerized chain MoOCl$_2$

Abstract

Using ab initio density functional theory, here we systematically study the monolayer MoOCl2 with a 4d 2 electronic configuration. Our main results is that an orbital-selective Peierls phase (OSPP) develops in MoOCl2, resulting in the dimerization of the Mo chain along the b-axis. Specifically, the Mo-dxy orbitals form robust molecular-orbital states inducing localized dxy singlet dimers, while the Mo-d xz/yz orbitals remain delocalized and itinerant. Our study shows that MoOCl2 is globally metallic, with the Mo-dxy orbital bonding-antibonding splittings opening a gap and the Mo-d xz/yz orbitals contributing to the metallic conductivity. Overall, the results resemble the recently much discussed orbital-selective Mott phase but with the localized band induced by a Peierls distortion instead of Hubbard interactions. Finally, we also qualitatively discuss the possibility of OSPP in the 3d 2 configuration, as in CrOCl2.

Magnetic states of quasi-one-dimensional iron chalcogenide Ba$_2$FeS$_3$

“…One-dimensional material systems continue attracting considerable attention due to their rich physical properties, where the charge, spin, orbital, and lattice degrees of freedom are intertwinned in a reduced dimensional phase space [1][2][3][4]. Remarkable physical phenomena have been reported in different one-dimensional systems, such as high critical temperature superconductivity in copper chains and ladders [5][6][7], ferroelectricity [8][9][10], spin block states [11,12], nodes in spin density [13], orbital ordering [14,15], orbital-selective Mott phases [16,17], and charge density wave or Peierls distortions [10,[18][19][20].…”