We grow MnAl films on different underlayers by molecular beam epitaxy (MBE), and investigate their structural and magnetic properties. L1(0)-ordered MnAl films were successfully grown both on an MgO (0 0 1) single-crystalline substrate and on an Mn4N(0 0 1) buffer layer formed on MgO(0 0 1) and SrTiO3(0 0 1) substrates. For the MgO substrate, post rapid thermal annealing (RTA) drastically improved the crystalline quality and the degree of L1(0)-ordering, whereas no improvement in the crystallinity was achieved by altering the substrate temperature (T-S) during MBE growth. However, high-quality L1(0)-MnAl films were formed on the Mn4N buffer layer by simply varying T-S. Structural analysis using X-ray diffraction showed MnAl on an MgO substrate had a cubic structure whereas MnAl on the Mn4N buffer had a tetragonal structure. This difference in crystal structure affected the magnetic properties of the MnAl films. The uniaxial magnetic anisotropy constant (K-u) was drastically improved by inserting an Mn4N buffer layer. We achieved a perpendicular magnetic anisotropy of K-u = 5.0 +/- 0.7 Merg/cm(3) for MnAl/Mn4N film on MgO and 6.0 +/- 0.2 Merg/cm(3) on STO. These results suggest that Mn4N has potential as an underlayer for L1(0)-MnAl. (C) 2018 Elsevier B.V. All rights reserved.