Impact of antiferromagnetic order on Landau-level splitting of quasi-two-dimensional Dirac fermions in EuMnBi2

Abstract

We report spin-split Landau levels of quasi-two-dimensional Dirac fermions in a layered antiferromagnet EuMnBi 2 , as revealed by interlayer resistivity measurements in a tilted magnetic field up to ∼35 T. The amplitude of Shubnikov-de Haas (SdH) oscillation in interlayer resistivity is strongly modulated by changing the tilt angle of the field, i.e., the Zeeman-to-cyclotron energy ratio. The effective g factor estimated from the tilt angle, where the SdH oscillation exhibits a phase inversion, differs by approximately 50% between two antiferromagnetic phases. This observation signifies a marked impact of the magnetic order of Eu sublattice on the Dirac-like band structure.The origin may be sought in strong exchange coupling with the local Eu moments, as verified by the first-principles calculation.

Enhanced magnetopiezoelectric effect at the Néel temperature in CaMn2Bi2

“…The MPE proposed by Watanabe et al [19] was first experimentally demonstrated for the antiferromagnetic metal EuMnBi 2 by some of the present authors by measuring currentinduced displacements with use of laser Doppler vibrometry [21]. EuMnBi 2 is a layered compound, where the conducting layers of Bi square net and the insulating magnetic layers consisting of Mn-Bi and Eu layers are spatially separated [22][23][24][25][26]. The transport property is quasi two-dimensional, and a quantum Hall effect is observed at the very low temperatures thanks to very high electron mobility in the c plane [23].…”

Angular Dependence of Interlayer Magnetoresistance for Antiferromagnetic Dirac Semimetal AMnBi2 (A = Sr, Eu)

“…splitting in the Dirac-like band [10]. At low fields below 2.5 T, such spin-splitting should be negligible owing to the small in-plane magnetization, resulting in the B dependence of r similar to that for SrMnBi 2 .…”

“…We obtained platelike crystals with a typical size of 5 mm × 5 mm × 1 mm for both materials. Interlayer resistivity was measured with a conventional four-terminal method [8,10]. For low-noise resistivity measurements, we adopted an AC lock-in method with an excitation current of 0.5 mA at 103 Hz.…”

“…In EuMnBi 2 , on the other hand, the transport properties are strongly affected by the Eu magnetism [8,9], because the local Eu spins adjacent to the Bi square net are coupled with the Dirac fermion states via the exchange interaction [10]. In fact, the interlayer conduction can be suppressed by about an order of magnitude by the field-induced flop of the Eu spins, which exhibit the A-type antiferromagnetic order shown in Fig.…”

“…1(a) at the ground state at zero field. As for the Fermi surface, similarly to SrMnBi 2 , EuMnBi 2 hosts four anisotropic Dirac valleys on the Γ-M lines [8,10,11]. Therefore, the comparative study of the anisotropic interlayer MR for EuMnBi 2 and SrMnBi 2 would provide further insight on the impact of magnetism on interlayer conduction in these multilayered Dirac systems.…”