Signature of topological states in antiferromagnetic Sm-substituted Bi2Te3

Abstract

An antiferromagnetic topological insulator has been predicted to be preserved by breaking both timereversal symmetry and primitive lattice translational symmetry. However, the topological surface state has often been observed to disappear in an antiferromagnetic phase because the doped magnetic impurity acts as an extrinsic defect. in this study, we report the experimental signature of topological surface states coexisting with antiferromagnetic order in Sm-doped Bi 2 te 3. We fabricate single crystals of Sm x Bi 2−x te 3 with x = 0.004, 0.010, and 0.025, where the Curie-Weiss law is satisfied at low temperatures but is violated at high temperatures due to the influence of the high energy states of J multiplets of Sm. for x = 0.025, e xotic physical properties are observed, such as the antiferromagnetic phase with the néel temperature T n = 3.3 K, multi-band Hall effect with two conduction channel, and anisotropic Shubnikov-de Haas oscillations. in the antiferromagnetic phase, we detect the signature of nontrivial topological surface states with surface electron density n s = 7.9 × 10 11 cm −2 and its high mobility μ s = 2,200 cm 2 /Vs, compared to n b = 2.0 × 10 19 cm −3 and μ b = 2.3 cm 2 /Vs for bulk electrons. these observations suggest that Sm x Bi 2−x te 3 is a candidate creating the new stage for the potential application of topological antiferromagnetic spintronics.

Incipient antiferromagnetism in the Eu-doped topological insulatorBi2Te3

“…Whereas MnBi 2 Te 4 is a stoichiometric compound and the AFM order there is intrinsic, here we rather rely on RE doping of Bi 2 Te 3 to induce antiferromagnetism, not least to circumvent RE solubility issues. The general feasibility of this approach has been demonstrated for Ce z Bi 2−z Te 3 30 , Sm z Bi 2−z Te 3 31 and Gd z Bi 2−z Te 3 32 . As determined by magnetometry [30][31][32] , the onset of AFM interactions is achieved even at low RE concentrations (in case of Sm z = 0.025 already suffices).…”

“…The general feasibility of this approach has been demonstrated for Ce z Bi 2−z Te 3 30 , Sm z Bi 2−z Te 3 31 and Gd z Bi 2−z Te 3 32 . As determined by magnetometry [30][31][32] , the onset of AFM interactions is achieved even at low RE concentrations (in case of Sm z = 0.025 already suffices). However, x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) investigations addressing the character of the magnetic moments and the impact on the TSS are scarce 33 and limited to temperatures nearly an order of magnitude above the AFM onset temperature, which calls for further investigations.…”