Coupled spin-charge order in frustrated itinerant triangular magnets

TL;DR

This paper discovers four new spin-charge ordered ground states in frustrated triangular Kondo lattice models, revealing complex magnetic and charge patterns stabilized by electronic band effects, with relevance to real materials.

Contribution

It introduces four novel magnetic ground states in the strong coupling limit of the Kondo lattice model on triangular lattices, including a variant of the 120° Yafet-Kittel phase.

Findings

Four new spin-charge ordered ground states identified.

Charge order pattern at 2/3 filling observed in real materials.

Magnetic orders stabilized by electronic band gaps.

Abstract

We uncover four new spin-charge ordered ground states in the strong coupling limit of the Kondo lattice model on triangular geometry. Two of the states at one-third electronic filling ($n=1/3$) consist of decorated ferromagnetic chains coupled antiferromagnetically with the neighboring chains. The third magnetic ground state is noncollinear, consisting of antiferromagnetic chains separated by a pair of canted ferromagnetic chains. An even more unusual magnetic ground state, a variant of the $120^{\circ}$ Yafet-Kittel phase, is discovered at $n=2/3$. These magnetic orders are stabilized by opening a gap in the electronic spectrum: a "band effect". All the phases support modulations in the electronic charge density due to the presence of magnetically inequivalent sites. In particular, the charge ordering pattern found at $n=2/3$ is observed in various triangular lattice systems, such as, 2H-AgNiO$_2$, 3R-AgNiO$_2$ and Na$_x$CoO$_2$.