Unusual Intralayer Ferromagnetism Between S = 5/2 ions in MnBi${}_2$Te${}_4$: Role of Empty Bi $p$ States

Abstract

The layered magnetic topological insulator MnBi${}_2$Te${}_4$ is a promising platform to realize the quantum anomalous Hall effect because its layers possess intrinsic ferromagnetism. However, it is not well understood why the high-spin $d^5$ magnetic ions Mn${}^{2+}$ forming the Mn-Te-Mn spin exchange paths prefer ferromagnetic (FM) coupling, contrary to the prediction of the Goodenough-Kanamori rule that a TM-L-TM spin exchange, where TM and L are a transition-metal magnetic cation and a main group ligand, respectively, is antiferromagnetic (AFM) even when the bond angle of the exchange path is 90${}^{\circ }$. Using density functional theory (DFT) calculations, we show that the presence of Bi${}^{3+}$ ions is essential for the FM coupling in MnBi${}_2$Te${}_4$. Then, using a tight-binding model Hamiltonian, we find that high-spin $d^5$ ions (S = 5/2) in TM-L-TM spin exchange paths prefer FM coupling if the empty p-orbitals of a nonmagnetic cation M (e.g., Bi${}^{3+}$ ion) hybridize strongly with those of the bridging ligand L, but AFM coupling otherwise.

13 pages, 4 figures

References in corpus (10)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Topological Field Theory of Time-Reversal Invariant Insulators
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Spin current and magneto-electric effect in non-collinear magnets
• Antiferromagnetic topological insulators
• Quantum Anomalous Hall Effect in Graphene Proximity Coupled to an Antiferromagnetic Insulator
• Crystal growth and magnetic structure of MnBi2Te4
• Spin-Orbital Entanglement and Violation of the Goodenough-Kanamori Rules
• Predicting a Ferrimagnetic Phase of Zn2FeOsO6 with Strong Magnetoelectric Coupling
• The electronic structures and magnetic properties of perovskite ruthenates from constrained orbital hybridization calculations

Cited by in corpus (4)

• Tunable interlayer magnetism and band topology in van der Waals heterostructures of MnBi2Te4-family materials
• Interlayer magnetophononic coupling in MnBi2Te4
• Magnetic Anisotropy in Two-dimensional van der Waals Magnetic Materials and Their Heterostructures: Importance, Mechanisms, and Opportunities
• Layer Zero-Line Modes in Antiferromagnetic Topological Insulators