Flat-Band Itinerant Antiferromagnetism in the Kagome Metal CoSn1-xInx

Abstract

Destructive interference of electron hopping on the frustrated kagome lattice generates Dirac nodes, saddle points, and flat bands in the electronic structure. The latter provides the narrow bands and a peak in the density of states that can generate correlated electron behavior when the Fermi level lies within them. In the kagome metal CoSn, this alignment is not realized, and the compound is a Pauli paramagnet. Here we show that replacing part of the tin with indium (CoSn1-xInx) moves the Fermi energy into the flat band region, with support from band structure calculations, heat capacity measurements, and angle resolved photoemission spectroscopy. The associated instability results in the emergence of itinerant antiferromagnetism with a Neel temperature up to 30K. Long range magnetic order is confirmed by neutron diffraction measurements, which indicate an ordered magnetic moment of 0.1-0.2 Bohr magnetons per Co (for x = 0.4). Thus, CoSn1-xInx provides a rare example of an itinerant antiferromagnet with a small ordered moment. This work provides clear evidence that flat bands arising from frustrated lattices in bulk crystals represent a viable route to new physics, evidenced here by the emergence of magnetic order upon introducing a non-magnetic dopant into a non-magnetic kagome metal.

References in corpus (8)

• High temperature fractional quantum Hall states
• Nearly-flat bands with nontrivial topology
• Theoretical prediction of a strongly correlated Dirac metal
• Fantastic flat bands and where to find them: The CoSn-type compounds
• Intrinsic anomalous Hall effect in Ni-substituted magnetic Weyl semimetal Co3Sn2S2
• Tuning the flat bands of the kagome metal CoSn with Fe, In, or Ni doping
• Revisiting the Kitaev material candidacy of Ir4+ double perovskite iridates
• A catastrophic charge density wave in BaFe${}_2$Al${}_9$

Cited by in corpus (10)

• A flat band-induced correlated kagome metal
• Tiny Sc allows the chains to rattle: Impact of Lu and Y doping on the charge density wave in ScV${}_6$Sn${}_6$
• Epitaxial Kagome Thin Films as a Platform for Topological Flat Bands
• Kagome metals
• Intricate magnetic landscape in antiferromagnetic kagome metal TbTi${}_3$Bi${}_4$ and interplay with Ln${}_{2-x}$Ti${}_{6+x}$Bi${}_9$ (Ln: Tb-Lu) shurikagome metals
• Electronic band structures of topological kagome materials
• Electronic orders on the kagome lattice at the lower Van Hove filling
• Double-layer Kagome Metals Pt3Tl2 and Pt3In2
• Evolution of electronic and magnetic properties in Mn- and Co-alloyed ferromagnetic kagome metal Fe3Sn2
• Frustration-free free fermions