Helimagnetism in MnBi2Se4 Driven by Spin-Frustrating Interactions Between Antiferromagnetic Chains

Abstract

We report the magnetic properties and magnetic structure determination for a linear-chain antiferromagnet, MnBi2Se4. The crystal structure of this material contains chains of edge-sharing MnSe6 octahedra separated by Bi atoms. The magnetic behavior is dominated by intrachain antiferromagnetic (AFM) interactions, as demonstrated by the negative Weiss constant of −74 K obtained by the Curie–Weiss fit of the paramagnetic susceptibility measured along the easy-axis magnetization direction. The relative shift of adjacent chains by one-half of the chain period causes spin frustration due to interchain AFM coupling, which leads to AFM ordering at TN = 15 K. Neutron diffraction studies reveal that the AFM ordered state exhibits an incommensurate helimagnetic structure with the propagation vector k = (0, 0.356, 0). The Mn moments are arranged perpendicular to the chain propagation direction (the crystallographic b axis), and the turn angle around the helix is 128°. The magnetic properties of MnBi2Se4 are discussed in comparison to other linear-chain antiferromagnets based on ternary mixed-metal halides and chalcogenides.

Incommensurate Spiral Spin Order in CaMn2Bi2 Observed via High-Pressure Neutron Diffraction

“…The term zigzag chains is used to describe adjacent chains that are shifted by 1/2 of the chain repeat distance, whereas ladder chains have aligned adjacent chains or without a shift. Quasi-1D structural chains provide a potentially unique platform for observing incommensurate spin ordering, including helimagnetic structures, observed in several ternary chalcogenides and halides, depending on the intra- and interchain interactions. − …”

Superlattices of Gadolinium and Bismuth Based Thallium Dichalcogenides as Potential Magnetic Topological Insulators

“…Another possibility is that the interlayer configuration is helimagnetic, which is compatible with the interlayer magnetic frustration [ 99 , 100 ]. It would also be in line with the results of the electron paramagnetic resonance study of TlGdSe [ 75 ], pointing towards a possible helimagnetic state.…”

“…It is thus evident that the exact 3D magnetic ground state structure of both TlGdTe and TlGdSe is very difficult to determine using the DFT calculations. The neutron diffraction measurements, which is a standard tool used to resolve magnetic structures in experiment [ 65 , 99 ], are desirable for TlGd .…”

2D spin glass MnIn2Se4: application of liquid-phase exfoliation to a layered structure with seven-atom-thick layers

“…Such deviation is explained by partial quenching of the Mn magnetic moment due to the covalency of the Mn-Se bonds. [32][33][34] The negative Weiss constant, y = -81.7(1) K, indicates antiferromagnetic (AFM) interactions between the Mn 2+ ions. Despite this relatively strong exchange coupling, the material does not exhibit AFM ordering, in agreement with the previous reports.…”