Anisotropy of exchange interactions in honeycomb ladder compound ReCl5

TL;DR

This study investigates the magnetic anisotropy and exchange interactions in ReCl5, revealing complex antiferromagnetic ordering, metamagnetic transitions, and anisotropic exchange couplings within a honeycomb ladder structure.

Contribution

It provides the first detailed analysis of anisotropic exchange interactions and magnetic ordering in ReCl5, combining experimental measurements with ab initio calculations.

Findings

ReCl5 exhibits two-step antiferromagnetic ordering at 35.5 K and 13.2 K.

Weak magnetic fields induce a metamagnetic transition at 4 K.

Ab initio calculations reveal anisotropic ferromagnetic exchange interactions J1 and J2 within Re pairs.

Abstract

The Re5+(5d2) compounds possess large spin-orbital interaction which urges for large anisotropy, non-collinear structures and other phenomena. Here we present ReCl5 composed by separate Re2Cl10 units formed by edge-shared chlorine octahedra. It demonstrates the formation of antiferromagnetically ordered state in two steps at TN1 = 35.5 K and TN2 = 13.2 K seen in dc-, ac-magnetic susceptibility and in specific heat. At 4K it can be transformed to the state with spontaneous magnetic moment by relatively weak magnetic field m0H = 0.5 T via metamagnetic phase transition. Ab initio calculations give anisotropic ferromagnetic exchange interactions J1 and J2 within and between rhenium pairs forming the zig-zag chains along the a-axis. Pairs of zig-zag chains are coupled by ferromagnetic interaction J3 along the c-axis into magnetic honeycomb ladders. The ladders are coupled by significantly weaker interaction J4.