We explore magnetic tunnel junctions consisting of Co60Fe40/AlOx/Co2FeSi trilayers on Si(111) by room-temperature molecular beam epitaxy. Even for the all room-temperature fabrication processes, the Co2FeSi layer includes L2(1)-ordered structures. We demonstrate reproducible tunneling magnetoresistance ratios of similar to 44% and similar to 28% at 30 K and 300 K, respectively. Assuming the same room-temperature spin polarization (P) of CoFe alloys, P for Co2FeSi grown at room temperature is larger than that for DO3-Fe3Si grown at 130 degrees C. (c) 2013 Elsevier B.V. All rights reserved.