MnRhBi<sub>3</sub>: A Cleavable Antiferromagnetic\nMetal

Cleavable metallic antiferromagnets may be of use for\nlow-dissipation\nspintronic devices; however, few are currently known. Here we present\northorhombic MnRhBi<sub>3</sub> as one such compound and present a\nthorough study of its physical properties. Exfoliation is demonstrated\nexperimentally, and the cleavage energy and electronic structure are\nexamined by density functional theory calculations. It is concluded\nthat MnRhBi<sub>3</sub> is a van der Waals-layered material that cleaves\neasily between neighboring Bi layers and that the Bi atoms have lone\npairs extending into the van der Waals gaps. A series of four phase\ntransitions are observed below room temperature, and neutron diffraction\nshows that at least two of the transitions involve the formation of\nantiferromagnetic order. Anomalous thermal expansion points to a crystallographic\nphase transition and/or strong magnetoelastic coupling. This work\nreveals a complex phase evolution in MnRhBi<sub>3</sub> and establishes\nthis cleavable antiferromagnetic metal as an interesting material\nfor studying the interplay of structure, magnetism, and transport\nin the bulk and ultrathin limits, as well as the role of lone pair\nelectrons in interface chemistry and proximity effects in van der\nWaals heterostructures.