研究目的
To manipulate Majorana fermions by depositing superconducting materials on the surfaces of topological insulators, specifically fabricating high-quality superconducting PdTe2 films on Bi2Te3 using molecular beam epitaxy.
研究成果
High-quality PdTe2/Bi2Te3 heterostructures with atomically sharp interfaces are successfully fabricated using MBE. PdTe2 films exhibit electron donor behavior, shifting the Dirac point of Bi2Te3 by 40 meV, and show superconductivity at ~1.4 K. This method enables the deposition of superconducting materials on TI surfaces with low defect density, facilitating the design of nanodevices for manipulating Majorana fermions. Future work should explore the superconductivity of uncovered Bi2Te3 and other material candidates like PdTe.
研究不足
The growth mode of PdTe2 films on Bi2Te3 is spiral rather than ideal layer-by-layer, which may introduce defects. The superconductivity transition temperature is low (~1.4 K), and the intrinsic superconductivity of uncovered Bi2Te3 regions requires further investigation. The method may not be applicable to other superconducting materials with higher growth temperatures.
1：Experimental Design and Method Selection:
The study uses molecular beam epitaxy (MBE) to grow PdTe2 films on Bi2Te3 under Te-rich conditions, with in situ scanning tunneling microscopy/spectroscopy (STM/STS) for surface and electronic property analysis, and ex situ two-coil mutual inductance technique for superconductivity detection.
2：Sample Selection and Data Sources:
Epitaxial graphene on 6H-SiC (0001) is used as the substrate for growing Bi2Te3 and PdTe2 films. Samples include Bi2Te3 films (25 nm thick), PdTe2 films (6 nm and 12 nm thick), and PdTe2/Bi2Te3 heterostructures.
3：List of Experimental Equipment and Materials:
Equipment includes a Unisoku low-temperature STM combined with MBE system, electron-beam evaporator for Pd, Knudsen cells for Bi and Te, electrochemically etched tungsten tips modified at Ag (111) surface, and a two-coil mutual inductance setup. Materials include Pd (
4：95%), Bi (9999%), Te (9999%), and 6H-SiC substrate. Experimental Procedures and Operational Workflow:
Bi2Te3 films are grown by co-depositing Bi and Te under Te-rich conditions at 260°C. PdTe2 films are similarly grown under Te-rich conditions. STM/STS measurements are performed at 78 K with lock-in technique. Superconductivity is measured from
5：4 K to 6 K. Data Analysis Methods:
STM images and line profiles are analyzed for topography and step heights. dI/dV spectra are analyzed for electronic properties. Magnetization data is fitted with exponential functions to determine superconducting transition temperature.
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