Suppressed weak antilocalization in the topological insulator Bi₂Se₃proximity coupled to antiferromagnetic NiO

Abstract

Time-reversal symmetry (TRS) breaking of the topological insulators (TIs) is a prerequisite to observe the quantum anomalous Hall effect (QAHE) and topological magnetoelectric effect (TME). Although antiferromagnetism as well as ferromagnetism could break the TRS and generate massive Dirac surface states in the TIs, no attention has been paid to the antiferromagnet-TI heterostructures. Herein, we report the magnetotransport measurements of BiSe proximately coupled to antiferromagnetic NiO. Thin films of BiSe were successfully grown on the NiO (001) single crystalline substrates by molecular beam epitaxy. Unexpectedly, we observed a strong suppression of the weak antilocalization effect, which is similar to the case of TIs coupled to the ferromagnetic materials. For the 5 nm-thick BiSe sample on NiO, we even observed a crossover to weak localization at 2 K. These behaviors are attributed to the strong magnetic exchange field from the Ni 3d electrons. Our results show the effectiveness of the antiferromagnetic materials in breaking the TRS of TIs by the proximity effect and their possible applications for QAHE and TME observations.

Recent Progress in Proximity Coupling of Magnetism to Topological Insulators

“…Magnetotransport in such a heterostructure (NiO–Bi 2 Se 3 ) showed suppressed WAL, and even WL at a low magnetic field in a sample with ultrathin (5 nm) TI. [ 115 ] Whereas these results are encouraging, in order to unambiguously detect the proximity effect, further experimental investigations are necessary.…”

“…When a clean interface is obtained between a TI and a MM, the magnetic moments in the MM can align spins in parallel [ 104 ] or antiparallel [ 109 ] manner in the TI through direct exchange interaction. [ 109–116 ] This interaction requires direct wavefunction overlap and hence is inherently short ranged; thus for the TI surface state which decays exponentially into the TI bulk, the magnetization decays rapidly as well. [ 105 ] Similarly, only the magnetic moments of the layer next to the MM have any relevant impact.…”

Hybrid spintronic materials: Growth, structure and properties

“…Kandala et al performed electrical transport measurement of GdN/Bi2Se3, finding that a GdN overlayer results in suppression of weak anti-localization at the top surface of Bi2Se3 [492]. Similar observation of the suppressed weak antilocalization in Bi2Se3 proximity coupled to antiferromagnetic NiO was reported by Bhowmick et al[493]. By demonstrating the MR effect, Yang et al[494] and Wei et al[492] observed proximity-induced ferromagnetism at the interface of EuS/Bi2Se3 prepared via both PLD and MBE deposition techniques respectively, although the effect observed is limited to low temperature (< 22 K) due to the low Tc of EuS.…”

Recent Progress in Proximity Coupling of Magnetism to Topological Insulators

“…Surprisingly, tight-binding calculations by Oroszlány and Cortijo showed that even anantiferromagnetic interface with staggered magnetization can lead to proximityinduced gap opening in TI surface states [183], making AFMI-TI heterostructures even more promising. Mag-netotransport in such a heterostructure (NiO-Bi 2 Se 3 ) showed suppressed WAL, and even WL at a low magnetic field in a sample with ultrathin (5 nm) TI [108]. Whereas these results are encouraging, in order to unambiguously detect the proximity effect, further experimental investigations are necessary.…”

“…When a clean interface is obtained between a TI and a MM, the magnetic moments in the MM can align spins in parallel or antiparallel manner in the TI through direct exchange interaction [102][103][104][105][106][107][108][109]. This interaction requires direct wavefunction overlap and hence is inherently short ranged; thus for the TI surface state which decays exponentially into the TI bulk, the magnetization decays rapidly as well [98].…”