Low-dimensional materials exhibit exotic properties and have attracted widespread attention. However, many low-dimensional materials are highly sensitive to air, making it challenging to investigate their intrinsic properties with ex situ measurements. To overcome such challenges, here, we developed a system combined with sample growth, electrode deposition, and in situ electrical transport measurement under ultra-high vacuum condition. The in situ deposition of electrodes enables desired ohmic electrical contacts between the probes and samples, which allows continuous temperature dependent resistance (R–T) measurements. Combined with a scanning tunneling microscope, surface morphology, electronic structure, and electrical transport properties of the same sample can be systematically investigated. We demonstrate the performance of this in situ electrical transport measurement system with three-unit-cell thick FeSe films grown on Nb-doped SrTiO3(001) substrates, where a low-noise R–T curve with a zero-resistance superconducting transition temperature of ∼30 K is observed.
Superconducting quantum devices, due to their ultra-low power consumption, high sensitivity and high speed, have attracted great attention in recent years and put forward higher requirements for fabrication technology. Here, we report on the first superconducting ultrathin FeSe nanowires on SrTiO3 substrates successfully fabricated by electron beam lithography and Ar plasma ion beam etching. As the superconductivity of the molecular beam epitaxial ultrathin FeSe film is highly susceptible by moisture and oxygen, FeTe layers were deposited for protection. We synthesized a superconducting ∼300 nm wide, ∼1.1 nm thick ultrathin FeSe nanowire with
T
C
Zero
≈
5
K
(the critical temperature of zero resistance), as revealed by electrical transport measurements. The proper synthesis conditions of the high-quality ultrathin superconducting FeSe nanowires on SrTiO3 substrates are evaluated by analyzing the morphology and physical properties of the ∼300 nm width ultrathin FeSe nanowire. Our work may pave the way for future applications of air-sensitive iron-based superconducting films.
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