Influence of chemical stability on the fabrication of MnGa-based devices

TL;DR

This study systematically investigates the chemical stability of MnGa ferromagnetic films in various common fabrication chemicals and plasma, providing essential guidelines for their integration into spintronic devices.

Contribution

It offers new insights into the chemical resistance of MnGa films, crucial for micro-/nano-fabrication processes in spintronics.

Findings

MnGa is stable in acetone and ethanol.

Deionized water and acids attack MnGa violently.

Oxygen plasma passivates the MnGa surface by oxidation.

Abstract

Ferromagnetic films of L10-ordered MnGa have shown promise not only in the applications in ultrahigh-density magnetic recording and spintronic memories, oscillators, and sensors, but also in controllable studies of novel electrical transport phenomena. However, the stability of MnGa in chemicals and oxygen plasma that are commonly used in the standard micro-/nano-fabrication process has unsettled. In this work, we report a systematic study on the chemical stability of the MnGa films in acids, acetone, ethanol, deionized water, tetramethylammonium hydroxide (TMAOH) and oxygen plasma. We find that MnGa is very stable in acetone and ethanol, while can be attacked substantially if soaked in TMAOH solution for sufficiently long time. Deionized water and acids (e.g., HCl, H3PO4 and H2SO4 solutions) attack MnGa violently and should be avoided whenever possible. In addition, oxygen plasma can passivate the MnGa surface by oxidizing the surface. These results provide important information for the fabrication and the integration of MnGa based spintronic devices.