Synthesis of as-grown superconducting MgB_2 thin films by molecular beam epitaxy in UHV conditions

TL;DR

This paper reports the successful synthesis of superconducting MgB_2 thin films via molecular beam epitaxy under ultra-high vacuum, demonstrating their structural and superconducting properties on various substrates.

Contribution

It introduces a novel low-rate co-evaporation MBE method for growing MgB_2 films with superconductivity at 36K, highlighting the effects of buffer layers.

Findings

MgB_2 films exhibit superconductivity with T_c around 36K.

Films show three-dimensional growth as indicated by RHEED.

Clear Meissner effect observed below T_c.

Abstract

As-grown superconducting MgB_2 thin films have been grown on SrTiO_3(001), MgO(001), and Al_2O_3(0001) substrates by a molecular beam epitaxy (MBE) method with novel co-evaporation conditions of low deposition rate in ultra-high vacuum. The structural and physical properties of the films were studied by RHEED, XRD, electrical resistivity measurements, and SQUID magnetometer. The RHEED patterns indicate three-dimensional growth for MgB_2. The highest T_c determined by resistivity measurement was about 36K in these samples. And a clear Meissner effect below T_c was observed using magnetic susceptibility measurement. We will discuss the influence of B buffer layer on the structural and physical properties.