Heavily Cr-doped (Bi,Sb)<sub>2</sub>Te<sub>3</sub> as a ferromagnetic insulator with electrically tunable conductivity

Ou, Yunbo; Liu, Chang; Zhang, Liguo; Feng, Yang; Jiang, Gaoyuan; Zhao, Dongyang; Zang, Yunyi; Zhang, Qinghua; Gu, Lin; Wang, Yayu; He, Ke; Ma, Xu-Cun; Xue, Qi‐Kun

doi:10.1063/1.4960111

Cited by 17 publications

(10 citation statements)

References 19 publications

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“…The singly V‐doped film (Figure a) shows similar ρ yx but rather large ρ xx (8.6 h / e 2 at 1.5 T). The large ρ xx is probably because the V‐doped (Bi,Sb) 2 Te 3 film is near the boundary between the QAH and ordinary insulator phases, since the V‐doped films exhibiting unambiguous QAH effect either have lower V concentration or higher thickness (see the Supporting Information) . Codoping a small amount of Cr ( y = 0.05) in V‐doped film significantly promotes the QAH state: ρ yx is elevated to 0.88 h / e 2 (Figure b) and ρ xx is reduced to 0.54 h / e 2 (Figure i).…”

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confidence: 99%

Enhancing the Quantum Anomalous Hall Effect by Magnetic Codoping in a Topological Insulator

et al. 2017

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The quantum anomalous Hall (QAH) effect, which has been realized in magnetic topological insulators (TIs), is the key to applications of dissipationless quantum Hall edge states in electronic devices. However, investigations and utilizations of the QAH effect are limited by the ultralow temperatures needed to reach full quantization-usually below 100 mK in either Cr- or V-doped (Bi,Sb) Te of the two experimentally confirmed QAH materials. Here it is shown that by codoping Cr and V magnetic elements in (Bi,Sb) Te TI, the temperature of the QAH effect can be significantly increased such that full quantization is achieved at 300 mK, and zero-field Hall resistance of 0.97 h/e is observed at 1.5 K. A systematic transport study of the codoped (Bi,Sb) Te films with varied Cr/V ratios reveals that magnetic codoping improves the homogeneity of ferromagnetism and modulates the surface band structure. This work demonstrates magnetic codoping to be an effective strategy for achieving high-temperature QAH effect in TIs.

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Enhancing the Quantum Anomalous Hall Effect by Magnetic Codoping in a Topological Insulator

et al. 2017

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“…For instance, a sizable bulk band gap in 3D TIs is essential for realizing many exotic phenomena and fabricating new quantum devices that can operate at room temperature. Furthermore, due to the fact that intrinsic defects prevail in most TIs, the observation and realization of the surface state-dominated phenomena demands dedicated fine-tuning of the chemical composition, such as the quantum anomalous Hall effect observed in Cr x (Bi 1– y Sb y ) 2– x Te 3 …”

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High-Throughput Screening and Automated Processing toward Novel Topological Insulators

Zhang

et al. 2018

J. Phys. Chem. Lett.

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The bottleneck of current studies on topological insulators is to identify better materials that can be fabricated into devices more feasibly. To search for novel topological materials, we developed a high-throughput framework that can be utilized to screen for candidates with known crystal structures and further showcase topological properties based on automated construction of Wannier functions. We have applied our methods to ternary compounds of Bi, Sb, and nitrides as a representative sample. The topological properties are characterized by the surface states, verified by auxiliary evaluation of the Z 2 topological invariant. We successfully identified seven topological insulators. Our work paves the way to design novel topological materials.

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“…Both of them are FM insulators with an outof-plane easy axis, and have a good lattice match with the Bi 2 Te 3 family materials. CBST with 0.2 < x < 0.4 has T c = 40-90 K and H c 1 ∼ 0.1 T [59]. VBST with 0.1 < x < 0.3 has T c = 20-100 K and H c 2 ∼ 1.0 T [47].…”

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confidence: 99%

“…m 0 ∼ 0-50 meV depends on film thickness [60]. λ ∼ 30-100 meV is tunable by changing the magnetic ion doping concentration [59]. To ensure stable QAH state, λ m 0 .…”

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Controllable Majorana fermions on domain walls of a magnetic topological insulator

Wang

2018

Phys. Rev. B

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We propose to realize a one-dimensional chiral topological superconducting state at the magnetic domain walls stripe of a magnetic topological insulator coupled with a conventional s-wave superconductor. The localized Majorana zero modes can be constructed in a reconfigurable manner through magnetic domain writing by magnetic force microscopy. This proposal could be further extended to the Majorana zero modes at domain walls on superconducting spin-helical Dirac surface states, and may be applicable to the two-dimensional time-reversal invariant topological superconductor on FeTe0.5Se0.5 surface.

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Heavily Cr-doped (Bi,Sb)₂Te₃ as a ferromagnetic insulator with electrically tunable conductivity

Cited by 17 publications

References 19 publications

Enhancing the Quantum Anomalous Hall Effect by Magnetic Codoping in a Topological Insulator

Enhancing the Quantum Anomalous Hall Effect by Magnetic Codoping in a Topological Insulator

High-Throughput Screening and Automated Processing toward Novel Topological Insulators

Controllable Majorana fermions on domain walls of a magnetic topological insulator

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Heavily Cr-doped (Bi,Sb)2Te3 as a ferromagnetic insulator with electrically tunable conductivity

Cited by 17 publications

References 19 publications

Enhancing the Quantum Anomalous Hall Effect by Magnetic Codoping in a Topological Insulator

Enhancing the Quantum Anomalous Hall Effect by Magnetic Codoping in a Topological Insulator

High-Throughput Screening and Automated Processing toward Novel Topological Insulators

Controllable Majorana fermions on domain walls of a magnetic topological insulator

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Product

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Heavily Cr-doped (Bi,Sb)₂Te₃ as a ferromagnetic insulator with electrically tunable conductivity