Tsinghua University

Chinese Academy of Sciences

Xu-Cun Ma

Xi Chen

Ke He

Qi-Kun Xue

Li-Li Wang

Xiao Feng

Jin-Feng Jia

Cui-Zu Chang

Yao-Yi Li

Zhi Hong Li

Li Lv

Shuai-Hua Ji

Wen-Hao Zhang

Qing-Yan Wang

Ya-Yu Wang

A high-temperature superconducting film includes a SrTiOsubstrate, a single crystalline FeSe layer, and a protective layer with a layered crystal structure. The single crystalline FeSe layer is sandwiched between the SrTiOsubstrate and the protective layer via a layer-by-layer mode. An onset temperature of superconducting transition of the high-temperature superconducting film is greater than or equal to 54 K, and a critical current density of the high-temperature superconducting film is about 10A/cmat 12 K.

High-temperature superconducting film

A method for making a high-temperature superconducting film includes loading a SrTiOsubstrate in an ultra-high vacuum system. A single crystalline FeSe layer is grown on a surface of the SrTiOsubstrate by molecular beam epitaxy. A protective layer with a layered crystal structure is grown by molecular beam epitaxy and covering the single crystalline FeSe layer.

Method for making high-temperature superconducting film

A method for forming a topological insulator structure is provided. A strontium titanate substrate having a surface (111) is used. The surface (111) of the strontium titanate substrate is cleaned by heat-treating the strontium titanate substrate in the molecular beam epitaxy chamber. The strontium titanate substrate is heated and Bi beam, Sb beam, Cr beam, and Te beam are formed in the molecular beam epitaxy chamber in a controlled ratio achieved by controlling flow rates of the Bi beam, Sb beam, Cr beam, and Te beam. The magnetically doped topological insulator quantum well film is formed on the surface (111) of the strontium titanate substrate. The amount of the hole type charge carriers introduced by the doping with Cr is substantially equal to the amount of the electron type charge carriers introduced by the doping with Bi.

Method for making topological insulator structure

A method for generating quantum anomalous Hall effect is provided. A topological insulator quantum well film in 3QL to 5QL is formed on an insulating substrate. The topological insulator quantum well film is doped with a first element and a second element to form the magnetically doped topological insulator quantum well film. The doping of the first element and the second element respectively introduce hole type charge carriers and electron type charge carriers in the magnetically doped topological insulator quantum well film, to decrease the carrier density of the magnetically doped topological insulator quantum well film to be smaller than or equal to 1&#xd7;10cm. One of the first element and the second element magnetically dopes the topological insulator quantum well film. An electric field is applied to the magnetically doped topological insulator quantum well film to decrease the carrier density.

Method for generating quantized anomalous hall effect

An electrical device includes an insulating substrate and a magnetically doped TI quantum well film. The insulating substrate includes a first surface and a second surface. The magnetically doped topological insulator quantum well film is located on the first surface of the insulating substrate. A material of the magnetically doped topological insulator quantum well film is represented by a chemical formula of Cr(BiSb)Te, wherein 0&#x3c;x&#x3c;1, 0&#x3c;y&#x3c;2, and values of x and y satisfies that an amount of a hole type charge carriers introduced by a doping with Cr is substantially equal to an amount of an electron type charge carriers introduced by a doping with Bi, the magnetically doped topological insulator quantum well film is in 3 QL thickness to 5 QL thickness.

Electrical device having magnetically doped topological insulator quantum well film

A topological insulator structure includes an insulating substrate and a magnetically doped TI quantum well film located on the insulating substrate. A material of the magnetically doped TI quantum well film is represented by a chemical formula of Cr(BiSb)Te. 0.05&#x3c;x&#x3c;0.3, 0&#x3c;y&#x3c;0.3, and 1:2&#x3c;x:y&#x3c;2:1. The magnetically doped TI quantum well film is in 3 QL to 5 QL.

A topological insulator structure includes an insulating substrate and a magnetically doped TI quantum well film located on the insulating substrate. A material of the magnetically doped TI quantum well film is represented by a chemical formula of Cr(BiSb)Te. 0&#x3c;x&#x3c;1, 0&#x3c;y&#x3c;2. Values of x and y satisfies that an amount of a hole type charge carriers introduced by a doping with Cr is substantially equal to an amount of an electron type charge carriers introduced by a doping with Bi. The magnetically doped TI quantum well film is in 3 QL to 5 QL.

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Beijing, China

Xu-Cun Ma