Chiral/helical magnetic states in correlated Dirac and Weyl semimetals
ORAL · Invited
Abstract
Magnetic Dirac and Weyl semimetals, which host chiral fermions, provide an ideal platform for exploring the interplay between topological quantum states and electronic correlations. In this presentation, I will report several of our recent studies addressing a key question: Can novel magnetic orders emerge from the interaction between correlated chiral fermions and local magnetic moments?
Among a series of magnetic Dirac and Wey semimetal single crystals and thin films grown in our laboratory, we identified GdAlSi as a host of helical magnetic states, as evidenced by transport, magnetization, and resonant elastic x-ray scattering (REXS) measurements. Increasing chemical pressure by substituting Ge for Si induces a structural phase transition from the tetragonal structure of GdAlSi to the orthorhombic structure of GdAlGe. In GdAlGe, we again identified helical magnetic phases supported by density functional theory (DFT) calculations using anisotropic exchange-coupling constants.
Crystallizing in a hexagonal layered structure where triangular layers of Eu atoms alternate with honeycomb Au–Sb layers, EuAuSb is an odd parity altermagnet that hosts a chiral magnetic order below 3.9 K, in which ferromagnetic Eu layers rotate by 120° in-plane from one layer to the next. DFT calculations and angle-resolved photoemission spectroscopy (ARPES) measurements further indicate that EuAuSb has distinct spin-split bands. Remarkably, we observe a collapse of the spin-split Fermi surfaces in EuAuSb, driven by the weakening of short-range magnetic correlations and the exchange coupling between conduction electrons and local magnetic moments as temperature increases.
This work was carried out in collaboration with Antu Laha, Juntao Yao, Sarah Paone, Weiguo Yi, Niraj Aryal, John Tranquada, Jennifer Sears, and Asish Kundu. .
Among a series of magnetic Dirac and Wey semimetal single crystals and thin films grown in our laboratory, we identified GdAlSi as a host of helical magnetic states, as evidenced by transport, magnetization, and resonant elastic x-ray scattering (REXS) measurements. Increasing chemical pressure by substituting Ge for Si induces a structural phase transition from the tetragonal structure of GdAlSi to the orthorhombic structure of GdAlGe. In GdAlGe, we again identified helical magnetic phases supported by density functional theory (DFT) calculations using anisotropic exchange-coupling constants.
Crystallizing in a hexagonal layered structure where triangular layers of Eu atoms alternate with honeycomb Au–Sb layers, EuAuSb is an odd parity altermagnet that hosts a chiral magnetic order below 3.9 K, in which ferromagnetic Eu layers rotate by 120° in-plane from one layer to the next. DFT calculations and angle-resolved photoemission spectroscopy (ARPES) measurements further indicate that EuAuSb has distinct spin-split bands. Remarkably, we observe a collapse of the spin-split Fermi surfaces in EuAuSb, driven by the weakening of short-range magnetic correlations and the exchange coupling between conduction electrons and local magnetic moments as temperature increases.
This work was carried out in collaboration with Antu Laha, Juntao Yao, Sarah Paone, Weiguo Yi, Niraj Aryal, John Tranquada, Jennifer Sears, and Asish Kundu. .
*This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-SC0012704.
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Presenters
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Qiang Li
- Stony Brook University (SUNY)
- Brookhaven National Lab and Stony Brook University