标题： 超导LiFeAs薄膜在SrTiO3(001)衬底上的分子束外延生长 显示英文标题

标题： Molecular Beam Epitaxy Growth of Superconducting LiFeAs Film on SrTiO3(001) Substrate

摘要： 基于"111"化学计量比的铁基超导体LiFeAs近年来引起了广泛的研究兴趣。 首次我们通过分子束外延(MBE)在SrTiO3(001)衬底上成功生长了LiFeAs薄膜，并利用反射高能电子衍射(RHEED)和低温扫描隧道显微镜(LT-STM)研究了界面生长行为。 研究了衬底温度和Li/Fe通量比的影响。 形成了厚度仅为3个五层结构(QL)的均匀LiFeAs薄膜。 在4.7 K时，厚度超过4 QL的LiFeAs薄膜出现了超导能隙。当薄膜厚度超过13 QL时，由相干峰间距确定的超导能隙约为7 meV，接近块体材料的值。 厚LiFeAs薄膜的原位输运测量显示在约16 K附近出现尖锐的超导转变。通过温度依赖的磁阻效应估算了上临界场Hc2(0)=13.0 T。 LiFeAs薄膜的精确厚度和质量控制为生长类似的超薄铁砷化物薄膜铺平了道路。 显示英文摘要

摘要： The stoichiometric "111" iron-based superconductor, LiFeAs, has attacted great research interest in recent years. For the first time, we have successfully grown LiFeAs thin film by molecular beam epitaxy (MBE) on SrTiO3(001) substrate, and studied the interfacial growth behavior by reflection high energy electron diffraction (RHEED) and low-temperature scanning tunneling microscope (LT-STM). The effects of substrate temperature and Li/Fe flux ratio were investigated. Uniform LiFeAs film as thin as 3 quintuple-layer (QL) is formed. Superconducting gap appears in LiFeAs films thicker than 4 QL at 4.7 K. When the film is thicker than 13 QL, the superconducting gap determined by the distance between coherence peaks is about 7 meV, close to the value of bulk material. The ex situ transport measurement of thick LiFeAs film shows a sharp superconducting transition around 16 K. The upper critical field, Hc2(0)=13.0 T, is estimated from the temperature dependent magnetoresistance. The precise thickness and quality control of LiFeAs film paves the road of growing similar ultrathin iron arsenide films.