Reduced Dimensionality and Magnetic Frustration in KCr$_3$As$_3$

TL;DR

This study investigates the electronic and magnetic properties of KCr₃As₃, revealing a magnetic ground state with interlayer antiferromagnetic order, reduced dimensionality effects, and magnetic frustration relaxation leading to gapless excitations.

Contribution

It introduces a detailed analysis of the magnetic structure and frustration effects in KCr₃As₃, highlighting the role of reduced dimensionality and novel magnetic ordering.

Findings

Magnetic ground state with interlayer antiferromagnetic order

Fermi surface reduced to three one-dimensional sheets

Magnetic frustrations relaxed, leading to gapless spin excitations

Abstract

We study the electronic and magnetic structures of the newly-discovered compound KCr$_3$As$_3$. The non-magnetic state has five Fermi surface sheets involving respectively three quasi-one-dimensional and two three-dimensional energy bands. However, the ground state is magnetic, exhibiting a novel interlayer antiferromagnetic order where the basic block-spin state of a unit Cr triangle retains a high spin magnitude. Moreover, its Fermi surface involves three one-dimensional sheets only, providing evidence for local moments in this compound due to the reduced dimensionality. By fitting a twisted spin tube model the magnetic frustrations caused by local moments are found to be relaxed, leading to gapless spin excitations. A frustration-induced transition to the disordered low block-spin state is expected upon increasing the intralayer exchange interaction.