Quasi 2-D magnetism in the Kagome layer compound FeSn

TL;DR

This study investigates the magnetic, electronic, and structural properties of FeSn, a Kagome layer compound, revealing its complex 3D electronic structure, strong in-plane ferromagnetic interactions, and quasi-2D magnetic behavior.

Contribution

It provides comprehensive experimental and theoretical analysis of FeSn, highlighting its unique combination of 3D electronic structure and highly 2D magnetic properties.

Findings

FeSn exhibits ferromagnetic order within Kagome layers and antiferromagnetic order overall.

Resistivity measurements suggest FeSn's electronic structure is not purely quasi-2D.

DFT calculations reveal Dirac nodal lines and a 3D electronic structure.

Abstract

Single crystals of the single Kagome layer compound FeSn are investigated using x-ray and neutron scattering, magnetic susceptibility and magnetization, heat capacity, resistivity, Hall, Seebeck, thermal expansion, thermal conductivity measurements and density functional theory (DFT). FeSn is a planar antiferromagnet below TN = 365 K and exhibits ferromagnetic magnetic order within each Kagome layer. The in-plane magnetic susceptibility is sensitive to synthesis conditions. Resistivity, Hall and Seebeck results indicate multiple bands near the Fermi energy. The resistivity of FeSn is about 3 times lower for current along the stacking direction than in the plane, suggesting that transport and the bulk electronic structure of FeSn is not quasi 2D. FeSn is an excellent metal with Rho(300K)/Rho(2K) values about 100 in both directions. While the ordered state is antiferromagnetic, high temperature susceptibility measurements indicate a ferromagnetic Curie-Weiss temperature of 173 K, reflecting the strong in-plane ferromagnetic interactions. DFT calculations show a 3D electronic structure with the Dirac nodal lines along the K-H directions in the magnetic Brillouin zone about 0.3 eV below the Fermi energy, with the Dirac dispersions at the K points gapped by spin-orbit coupling except at the H point. The magnetism, however, is highly 2D with Jin-plane/Jout-of-plane = 10. The predicted spin-wave spectrum is presented.