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Realizing gapped surface states in the magnetic topological insulator Mn Bi 2 - x Sb x Te 4
The interplay between magnetism and nontrivial topology in magnetic topological insulators (MTIs) is expected to give rise to exotic topological quantum phenomena like the quantum anomalous Hall effect and the topological axion states. A key to assessing these novel properties is to realize gapped topological surface sates. MnBi 2 Te 4 possesses nontrivial band topology with an intrinsic antiferromagnetic state. However, the highly electron-doped nature of the MnBi 2 Te 4 crystals obstructs the exhibition of the surface band gap. Here, we tailor the material through Sb substitution to reveal the gapped surface states in MnBi 2-x Sb x Te 4 . By shifting the Fermi level into the bulk band gap, we access the surface states and show a band gap of 50 meV at the Dirac point from quasiparticle interference measured by scanning tunneling microscopy (STM). Surface-dominant conduction is confirmed through transport spectroscopy measured by multiprobe STM below the Néel temperature. The surface band gap is robust against the out-of-plane magnetic field despite the promotion of field-induced ferromagnetism. Finally, the realization of bulk-insulating MTIs with the large exchange gap offers a promising platform for exploring emergent topological phenomena.
Electron correlations in the cubic paramagnetic perovskite Sr ( V , Mn ) O 3 : Results from fully self-consistent self-energy embedding calculations
In this study, we use the thermodynamically consistent and conserving self-energy embedding theory (SEET) to study the spectra of the prototypical undistorted cubic perovskites SrVO 3 and SrMnO 3 . In the strongly correlated metallic SrVO 3 we find that the usual attribution of the satellite peaks at –1.8 eV to Hund or Hubbard physics in the t 2 g orbitals is inconsistent with our calculations. In the strongly correlated insulator SrMnO 3 we recover insulating behavior due to a feedback effect between the strongly correlated orbitals and the weakly correlated environment. Our calculation shows a systematic convergence of spectral features as the space of strongly correlated orbitals is enlarged, paving the way to a systematic parameter-free study of correlated perovskites.
Enhancement of the spin-glass transition temperature through p d -orbital hybridization in Zn 1 − x Mn x Te
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Magnetism and magnetotransport in the kagome antiferromagnet Mn 3 Ge
We perform classical Monte Carlo and stochastic Landau-Lifshitz-Gilbert simulations to study the temperature-dependent magnetism of the kagome antiferromagnet Weyl metal Mn3Ge, and we find that a long-range chiral order sets in at a transition temperature well below the Neel temperature (T N ). Based on the crystalline symmetries imposed by the chiral magnetic order, we argue for the presence of multiple isoenergetic Weyl nodes (nodes that are at the same energy and with a congruent Fermi surface around them) near the chemical potential. Using the semiclassical Boltzmann equations, we show that the combined contribution to the net longitudinal magnetoconductance (LMC) and the planar Hall conductance (PHC) from tilted Weyl nodes can lead to signatures that are qualitatively distinct from that of a single pair of Weyl nodes. In particular, we show that magnetic orders with different chiralities can give rise to different periods in LMC and PHC as a function of the in-plane magnetic field direction. As a result, this is ultimately related to differences in the symmetry-imposed constraints on the Weyl nodes.
Magnetization reversal induced by antiphase domain boundaries in Ni 2 Mn Z Heusler compounds
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Crystal size dependence of dipolar ferromagnetic order between Mn 6 molecular nanomagnets
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Possible evidence of Weyl fermion enhanced thermal conductivity under magnetic fields in the antiferromagnetic topological insulator Mn ( Bi 1 − x Sb x ) 2 Te 4
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Magnetoelectric coupling in the multiferroic hybrid-improper ferroelectric Ca 3 Mn 1.9 Ti 0.1 O 7
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Large anomalous Nernst effect and its bipolarity in the quaternary equiatomic Heusler alloys CrRu X Ge ( X = Co and Mn)
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Bulk and surface uniformity of magnetic and electronic structures in epitaxial W / Mn 3 Sn / MgO films revealed by fluorescence- and electron-yield x-ray magnetic circular dichroism
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Single-particle and collective excitations in the N = 28 isotones Fe 54 and Mn 53
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Rare Earth Engineering in R Mn 6 Sn 6 ( R = Gd–Tm, Lu) Topological Kagome Magnets
Exploration of the topological quantum materials with electron correlation is at the frontier of physics, as the strong interaction may give rise to new topological phases and transitions. Here we report that a family of kagome magnets RMn 6 Sn 6 manifest the quantum transport properties analogical to those in the quantum-limit Chern magnet TbMn 6 Sn 6 . The topological transport in the family, including quantum oscillations with nontrivial Berry phase and large anomalous Hall effect arising from Berry curvature field, points to the existence of Chern gapped Dirac fermions. Furthermore, our observation demonstrates a close relationship between rare-earth magnetism and topological electron structure, indicating the rare-earth elements can effectively engineer the Chern quantum phase in kagome magnets.
Strong anisotropy in the mixed antiferromagnetic system Mn 1 − x Fe x PSe 3
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First-principles study of magnetic states and the anomalous Hall conductivity of M Nb 3 S 6 ( M = Co, Fe, Mn, and Ni)
Here, inspired by the observation of the extremely large anomalous Hall effect in the absence of applied magnetic fields or uniform magnetization in CoNb 3 S 6 [Nat. Commun. 9, 3280 (2018); Phys. Rev. Research 2, 023051 (2020)], we perform a first-principles study of this and related compounds of the MNb 3 S 6 type with different transition metal M ions to determine their magnetic orders and the anomalous Hall conductivity (AHC). We find that noncoplanar antiferromagnetic ordering is favored relative to collinear or coplanar order in the case of M = Co, Fe, and Ni, while ferromagnetic ordering is favored in MnNb 3 S 6 at low temperatures. The AHC in these materials with noncoplanar spin ordering can reach about e 2 /h per crystalline layer, while being negligible for coplanar and collinear cases. We also find that the AHC depends sensitively on doping and reaches a maximum for intermediate values of the local spin exchange potential between 0.3 and 0.8 eV. Our AHC results are consistent with the reported Hall measurements in CoNb 3 S 6 and suggest a possibility of similarly large anomalous Hall effects in related compounds.
Structural defects in compounds ZnXSb (X = Cr, Mn, Fe): Origin of disorder and its relationship with
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Magnetic interactions in the one-dimensional spin-chain metal-organic compounds M ( N 2 H 5 ) 2 ( SO 4 ) 2 ( M = Cu , Co , Mn )
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Constraints on proximity-induced ferromagnetism in a Dirac semimetal ( Cd 3 As 2 ) / ferromagnetic semiconductor ( Ga 1 − x Mn x Sb ) heterostructure
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