Epitaxial growth of CoFe/Ge stacked structures on a perpendicularly magnetized MnGa alloy

Abstract For high density and low-power-consumption magnetoresistive random access memory applications, the combination of a low resistive tunnel barrier and perpendicularly magnetized magnetic layers is required. Here, we experimentally explore the growth of an all-epitaxial spin-valve structure with a perpendicularly magnetized MnGa alloy and semiconductor Ge. Using magnetron sputtering, solid phase epitaxy, and MBE methods, we stack the MnGa, Ge, and ferromagnetic CoFe layers, respectively. Although an unintentional Mn-based oxide layer is formed between MnGa and Ge, the Ge thin layer is able to be epitaxially grown even on the MnGa alloy. From the magnetometry, we find that the top CoFe and the bottom MnGa layers are magnetically decoupled and spin-valve like magnetization reversals are seen. This study enables us to fabricate a CoFe/Ge stacked structure on MnGa.