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Strain-modulated ferromagnetism and band gap of Mn doped Bi2Se3.

ABSTRACT: The quantized anomalous Hall effect (QAHE) have been theoretically predicted and experimentally confirmed in magnetic topological insulators (TI), but dissipative channels resulted by small-size band gap and weak ferromagnetism make QAHE be measured only at extremely low temperature (<0.1?K). Through density functional theory calculations, we systemically study of the magnetic properties and electronic structures of Mn doped Bi2Se3 with in-plane and out-of-plane strains. It is found that out-of-plane tensile strain not only improve ferromagnetism, but also enlarge Dirac-mass gap (up to 65.6?meV under 6% strain, which is higher than the thermal motion energy at room temperature ~26?meV) in the Mn doped Bi2Se3. Furthermore, the underlying mechanisms of these tunable properties are also discussed. This work provides a new route to realize high-temperature QAHE and paves the way towards novel quantum electronic device applications.

SUBMITTER: Qi S

PROVIDER: S-EPMC4931584 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

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Strain-modulated ferromagnetism and band gap of Mn doped Bi2Se3.

Qi Shifei S Yang Hualing H Chen Juan J Zhang Xiaoyang X Yang Yingping Y Xu Xiaohong X

Scientific reports 20160704

The quantized anomalous Hall effect (QAHE) have been theoretically predicted and experimentally confirmed in magnetic topological insulators (TI), but dissipative channels resulted by small-size band gap and weak ferromagnetism make QAHE be measured only at extremely low temperature (<0.1 K). Through density functional theory calculations, we systemically study of the magnetic properties and electronic structures of Mn doped Bi2Se3 with in-plane and out-of-plane strains. It is found that out-of- ...[more]

PMID: 27374782

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Project description:This work for the first time unfurls the fundamental mechanisms and sets the stage for an approach to derive electrocatalytic activity, which is otherwise not possible, in a traditionally known wide band-gap oxide material. Specifically, we report on the tunable optical properties, in terms of wide spectral selectivity and red-shifted band gap, and electrocatalytic behavior of iron (Fe)-doped gallium oxide (?-Ga2O3) model system. X-ray diffraction (XRD) studies of sintered Ga2-x Fe x O3 (GFO) (0.0 ? x ? 0.3) compounds provide evidence for the Fe3+ substitution at Ga3+ site without any secondary phase formation. Rietveld refinement of XRD patterns reveals that the GFO compounds crystallize in monoclinic crystal symmetry with a C2/m space group. The electronic structure of the GFO compounds probed using X-ray photoelectron spectroscopy data reveals that at lower concentrations, Fe exhibits mixed chemical valence states (Fe3+, Fe2+), whereas single chemical valence state (Fe3+) is evident for higher Fe content (x = 0.20-0.30). The optical absorption spectra reveal a significant red shift in the optical band gap with Fe doping. The origin of the significant red shift even at low concentrations of Fe (x = 0.05) is attributed to the strong sp-d exchange interaction originated from the 3d5 electrons of Fe3+. The optical absorption edge observed at ?450 nm with lower intensity is the characteristic of Fe-doped compounds associated with Fe3+-Fe3+ double-excitation process. Coupled with an optical band-gap red shift, electrocatalytic studies of GFO compounds reveal that, interestingly, Fe-doped Ga2O3 compound exhibits electrocatalytic activity in contrast to intrinsic Ga2O3. Fe-doped samples (GFO) demonstrated appreciable electrocatalytic activity toward the generation of H2 through electrocatalytic water splitting. An onset potential and Tafel slope of GFO compounds include ?900 mV, ?210 mV dec-1 (x = 0.15) and ?1036 mV, ?290 mV dec-1 (x = 0.30), respectively. The electrocatalytic activity of Fe-doped Ga-oxide compounds is attributed to the cumulative effect of different mechanisms such as doping resulting in new catalytic centers, enhanced conductivity, and electron mobility. Hence, in this report, for the first time, we explored a new pathway; the electrocatalytic behavior of Fe-doped Ga2O3 resulted due to Fe chemical states and red shift in the optical band gap. The implications derived from this work may be applicable to a large class of compounds, and further options may be available to design functional materials for electrocatalytic energy production.

Dataset Information

Strain-modulated ferromagnetism and band gap of Mn doped Bi2Se3.

Publications

Strain-modulated ferromagnetism and band gap of Mn doped Bi2Se3.

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