Presented By: Department of Physics
Special CM Theory Seminar | Study of the Dirac material candidates in high magnetic fields
Kuan-Wen Chen (Florida State University)
In this talk, I will focus on two series of Dirac candidates, (V,Nb,Ta)Al3 and CeSb(Se,Te). VAl_3 families are predicted as the type II Dirac semimetals where the Dirac bands are strongly tilted; therefore violate Lorentz-symmetry and have no analogue in high energy physics. CeSbTe were reported with multi Dirac/Weyl bands which can be tuned by magnetic fields.
By measuring de Hass-van Alphen effect using torque magnetomery in VAl_3 families. It revealed the existence of tilted Dirac cones with Dirac type-II nodes located at 100, 230 and 250 meV away from the Fermi level of VAl_3, NbAl_3, and TaAl_3, respectively. These results are consistent with earlier band structure calculations, which also predict a non-trivial electronic topology. However, for all three compounds we find that the cyclotron orbits on the Fermi surfaces, including an orbit nearly enclosing the Dirac type-II node, yield trivial Berry phases. We will show that in order to determine the Berry phases, the overall understanding of the topology of the Fermi surfaces and the g-factors are required.
CeSbSe shows magnetization plateaus between the antiferromagnetic states (M = 0) and the magnetization saturated states M_{sat}. The fractional plateau values of M/M_{sat} are equal to 1/6, 1/3, 5/12, 1/2, and 3/4. I will discuss a possible explanation between the magnetization plateaus and the magnetic structures of CeSbSe from the single crystal neutron diffraction data.
References:
[1] K.-W. Chen (1,2), X. Lian (1,2), Y. Lai (1,2), N. Aryal (1,2), Y.-C. Chiu (1,2), W. Lan (1,2), D. Graf (1), E. Manousakis (1,2), R. E. Baumbach (1,2), and L. Balicas (1,2), Phys. Rev. Lett. 120, 206401(2018).
[2] K.-W. Chen (1,2), Y. Lai (1,2), Y.-C. Chiu (1,2), S. Steven (3), T. Besara (1), D. Graf (1), T. Siegrist (1,4), T. E. Albrecht-Schmitt (3), L. Balicas (1,2), and R. E. Baumbach (1,2), Phys. Rev. B 96, 014421 (2017).
1 National High Magnetic Field Laboratory, Florida State University, Florida, USA
2 Department of Physics, Florida State University, Florida, USA
3 Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, USA
4 Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, Florida 32310, USA
By measuring de Hass-van Alphen effect using torque magnetomery in VAl_3 families. It revealed the existence of tilted Dirac cones with Dirac type-II nodes located at 100, 230 and 250 meV away from the Fermi level of VAl_3, NbAl_3, and TaAl_3, respectively. These results are consistent with earlier band structure calculations, which also predict a non-trivial electronic topology. However, for all three compounds we find that the cyclotron orbits on the Fermi surfaces, including an orbit nearly enclosing the Dirac type-II node, yield trivial Berry phases. We will show that in order to determine the Berry phases, the overall understanding of the topology of the Fermi surfaces and the g-factors are required.
CeSbSe shows magnetization plateaus between the antiferromagnetic states (M = 0) and the magnetization saturated states M_{sat}. The fractional plateau values of M/M_{sat} are equal to 1/6, 1/3, 5/12, 1/2, and 3/4. I will discuss a possible explanation between the magnetization plateaus and the magnetic structures of CeSbSe from the single crystal neutron diffraction data.
References:
[1] K.-W. Chen (1,2), X. Lian (1,2), Y. Lai (1,2), N. Aryal (1,2), Y.-C. Chiu (1,2), W. Lan (1,2), D. Graf (1), E. Manousakis (1,2), R. E. Baumbach (1,2), and L. Balicas (1,2), Phys. Rev. Lett. 120, 206401(2018).
[2] K.-W. Chen (1,2), Y. Lai (1,2), Y.-C. Chiu (1,2), S. Steven (3), T. Besara (1), D. Graf (1), T. Siegrist (1,4), T. E. Albrecht-Schmitt (3), L. Balicas (1,2), and R. E. Baumbach (1,2), Phys. Rev. B 96, 014421 (2017).
1 National High Magnetic Field Laboratory, Florida State University, Florida, USA
2 Department of Physics, Florida State University, Florida, USA
3 Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, USA
4 Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, Florida 32310, USA
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