scholarly journals Magnetism-induced topological transition in EuAs3

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Erjian Cheng ◽  
Wei Xia ◽  
Xianbiao Shi ◽  
Hongwei Fang ◽  
Chengwei Wang ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Nodal Line ◽  
Photoemission Spectroscopy ◽  
Topological Transition ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Spin Polarized ◽  
Lifshitz Transition ◽  
Antiferromagnetic Ground State ◽  
Exotic Physics ◽  
Topological Semimetals

AbstractThe nature of the interaction between magnetism and topology in magnetic topological semimetals remains mysterious, but may be expected to lead to a variety of novel physics. We systematically studied the magnetic semimetal EuAs3, demonstrating a magnetism-induced topological transition from a topological nodal-line semimetal in the paramagnetic or the spin-polarized state to a topological massive Dirac metal in the antiferromagnetic ground state at low temperature. The topological nature in the antiferromagnetic state and the spin-polarized state has been verified by electrical transport measurements. An unsaturated and extremely large magnetoresistance of ~2 × 105% at 1.8 K and 28.3 T is observed. In the paramagnetic states, the topological nodal-line structure at the Y point is proven by angle-resolved photoemission spectroscopy. Moreover, a temperature-induced Lifshitz transition accompanied by the emergence of a new band below 3 K is revealed. These results indicate that magnetic EuAs3 provides a rich platform to explore exotic physics arising from the interaction of magnetism with topology.

scholarly journals Magnetism-induced topological transition in EuAs3

2020 ◽  
Author(s):  
Erjian Cheng ◽  
Wei Xia ◽  
Jie Xu ◽  
Chengwei Wang ◽  
Chuanying Xi ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Berry Phase ◽  
Magnetic Moments ◽  
Surface States ◽  
Nodal Line ◽  
Chiral Anomaly ◽  
Topological Transition ◽  
Spin Polarized ◽  
Exotic Physics ◽  
Topological Semimetals

Abstract The nature of the interaction between magnetism and topology in magnetic topological semimetals remains mysterious, but may be expected to lead to a variety of novel physics. We present ab initio band calculations, electrical transport and angle-resolved photoemission spectroscopy (ARPES) measurements on the magnetic semimetal EuAs3, demonstrating a magnetism-induced topological transition from a topological nodal-line semimetal in the paramagnetic or the spin-polarized state to a topological massive Dirac metal in the antiferromagnetic (AFM) ground state at low temperature, featuring a pair of massive Dirac points, inverted bands and topological surface states on the (010) surface. Shubnikov-de Haas (SdH) oscillations in the AFM state identify nonzero Berry phase and a negative longitudinal magnetoresistance (n-LMR) induced by the chiral anomaly, confirming the topological nature predicted by band calculations. When magnetic moments are fully polarized by an external magnetic field, an unsaturated and extremely large magnetoresistance (XMR) of ∼ 2×105 % at 1.8 K and 28.3 T is observed, likely arising from topological protection. Consistent with band calculations for the spin-polarized state, four new bands in quantum oscillations different from those in the AFM state are discerned, of which two are topologically protected. Nodal-line structures at the Y point in the Brillouin zone (BZ) are proposed in both the spin-polarized and paramagnetic states, and the latter is proven by ARPES. Moreover, a temperature-induced Lifshitz transition accompanied by the emergence of a new band below 3 K is revealed. These results indicate that magnetic EuAs3 provides a rich platform to explore exotic physics arising from the interaction of magnetism with topology.

scholarly journals Searching for a promising topological Dirac nodal-line semimetal by angle resolved photoemission spectroscopy

2021 ◽  
Author(s):  
Zhengwang Cheng ◽  
Zhilong Hu ◽  
Shaojian Li ◽  
Xinguo Ma ◽  
Zhifeng Liu ◽  
...  
Keyword(s):  
Band Structure ◽  
Heterogeneous Catalysts ◽  
Nodal Line ◽  
Photoemission Spectroscopy ◽  
High Symmetry ◽  
Dirac Fermions ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Topological Semimetals ◽  
Valence Bands ◽  
Band Crossing

Abstract Topological semimetals, in which conduction and valence bands cross each other at either discrete points or along a closed loop with symmetry protected in the momentum space, exhibited great potential in applications of optical devices as well as heterogeneous catalysts or antiferromagnetic spintronics, especially when the crossing points/lines matches Fermi level (EF). It is intriguing to find the “ideal” topological semimetal material, in which has a band structure with Dirac band-crossing located at EF without intersected by other extraneous bands. Here, by using angle resolved photoemission spectroscopy (ARPES), we investigate the band structure of the so-called “square-net” topological material ZrGeS. The Brillouin zone (BZ) mapping shows the Fermi surface (FS) of ZrGeS is composed by a diamond-shaped nodal line loop at the center of BZ and small electron-like Fermi pockets around X point. The Dirac nodal line band-crossing located right at EF, and shows clearly the linear Dirac band dispersions within a large energy range >1.5 eV below EF, without intersected with other bands. The obtained Fermi velocities and effective masses along Γ-X, Γ-M and M-X high symmetry directions were 4.5 ~ 5.9 eV•Å and 0 ~ 0.50 me, revealing an anisotropic electronic property. Our results suggest that ZrGeS, as a promising topological nodal line semimetal (TNLSM), could provide a promising platform to investigate the Dirac-fermions related physics and the applications of topological devising.

scholarly journals Dirac nodal surfaces and nodal lines in ZrSiS

2019 ◽  
Vol 5 (5) ◽  
pp. eaau6459 ◽  
Author(s):  
B.-B. Fu ◽  
C.-J. Yi ◽  
T.-T. Zhang ◽  
M. Caputo ◽  
J.-Z. Ma ◽  
...  
Keyword(s):  
Photoemission Spectroscopy ◽  
Dirac Fermions ◽  
Fermi Surfaces ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Nodal Lines ◽  
Nodal Points ◽  
Different Dimensions ◽  
Topological Semimetals ◽  
Symmetry Protected ◽  
Nodal Surfaces

Topological semimetals are characterized by symmetry-protected band crossings, which can be preserved in different dimensions in momentum space, forming zero-dimensional nodal points, one-dimensional nodal lines, or even two-dimensional nodal surfaces. Materials harboring nodal points and nodal lines have been experimentally verified, whereas experimental evidence of nodal surfaces is still lacking. Here, using angle-resolved photoemission spectroscopy (ARPES), we reveal the coexistence of Dirac nodal surfaces and nodal lines in the bulk electronic structures of ZrSiS. As compared with previous ARPES studies on ZrSiS, we obtained pure bulk states, which enable us to extract unambiguously intrinsic information of the bulk nodal surfaces and nodal lines. Our results show that the nodal lines are the only feature near the Fermi level and constitute the whole Fermi surfaces. We not only prove that the low-energy quasiparticles in ZrSiS are contributed entirely by Dirac fermions but also experimentally realize the nodal surface in topological semimetals.

Spin Polarized Photoemission from Fe On CU(100)

1991 ◽  
Vol 231 ◽  
Author(s):  
D.P. Pappas ◽  
K.-P. KÄmper ◽  
B.P. Miller ◽  
H. Hopster ◽  
D.E. Fowler ◽  
...  
Keyword(s):  
Low Energy ◽  
Photoemission Spectroscopy ◽  
Universal Curve ◽  
Exchange Splitting ◽  
Attenuation Length ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Minority Spin ◽  
Spin Polarized ◽  
The Difference ◽  
Majority Spin

AbstractThe spin resolved electronic structure of ultra-thin Fe films on Cu(100) was investigated using spin polarized angle resolved photoemission spectroscopy. All exchange splitting of the Fe ∆s band of 2.5 eV is observed for photon energies between 20 and 30 eV. ∆ peak at 6 eV binding energy which has been previously identified as a many-electron resonance was observed only after contamination of the films with oxygen. In addition, the spin dependent attenuation lengths for electrons in Fe were measured at 11, 19, and 40 eV above Ef. The attenuation length for the minority spin electrons was found to be shorter than that of the majority spin electrons. The difference between the two attenuation lengths was shown to increase at low energy. Short attenuation lengths of ≃3 monolayer were measured at II eV. The large increase of the attenuation length at low energy which is expected from the “universal curve” is not observed in Fe.

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