Dresden 2017 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 18: Transport: Topological Semimetals 1 (jointly with MA/TT)
DS 18.5: Vortrag
Dienstag, 21. März 2017, 10:45–11:00, HSZ 201
Quantum oscillation and Dirac fermion in BaZnBi2 system — •Kan Zhao and Philipp Gegenwart — Experimentalphysik VI, Center for Electronic Correlations and Magnetism, Augsburg University, 86159 Augsburg, Germany
Dirac semimetals represent new quantum states of matter and have stimulated intensive studies. AMnBi2(A = alkali earth/rare earth metal) is one of the established Dirac semimetals, with both antiferromagnetic order in MnBi4 layer and Dirac fermion in Bi square net layer.
To investigate how the magnetism interacts with Dirac fermions, we synthesized single crystals of SrZnBi2 and BaZnBi2. Being isostructural to SrMnBi2, SrZnBi2 shows no quantum oscillation in resistivity and magnetic susceptibility up to 14 T. However, BaZnBi2 shows clear multiple quantum oscillations down to 4 T in magnetic susceptibility. According to the temperature dependence of the oscillation amplitude after fast Fourier transformation (FFT), the effective electron mass is about 0.1me, comparable with that of BaMnBi2. In the resistivity measurement up to 14 T at 2 K clear SdH oscillations with main oscillation frequency 168T are observed. The frequency follows a 1/|cos(θ)| dependence (θ is the angle between magnetic field and c axis), indicating a quasi 2D Fermi surface. Band-structure calculations by I. Mazin, indicate that BaZnBi2 exhibits a unique structure feature and electronic structure, with a quasi Dirac band near the Fermi level. ARPES and high-field SdH measurements, to further characterize the Dirac fermions, are in progress.