Tuning the Dzyaloshinskii-Moriya Interaction in Fe/MgO-based Thin Films Abdul-Muizz Pradipto (1) and Kohji Nakamura (2)
(1) Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Indonesia
(2) Department of Physics Engineering, Mie University, Japan
Abstract
The development of spintronics technology has been in part accelerated by the discovery of the Tunneling Magnetoresistance (TMR) effect, which can be realized by sandwiching ferromagnetic metal layers by an insulating barrier, such as Fe/MgO/Fe multilayers. At the proximity between the two materials, i.e. between Fe and MgO, exotic magnetic and transport phenomena differing from those at the pure system can take place due to the interfacial effects. It has been a common knowledge that understanding and controlling these properties at the interfaces is crucial in order to reach an optimum design of spintronic devices. In this work, the Dzyaloshinskii-Moriya interaction (DMI) in Fe/MgO thin films is investigated by using the Density Functional Theory (DFT) approach as implemented in the Full-potential Linearized Augmented Plane Wave (FLAPW) method. An atomic layer of heavy metal element M (M=Os, Ir, Pt, and Au) is inserted in between the two materials to enhance the spin-orbit coupling strength. Our calculations show that the introduction of the heavy metal layer alters the sign of DMI which implies the change in the magnetic chirality. When an external electric field associated to the application of electric gate voltages is introduced, the value of DMI is modified, and the modification is related to the change in the orbital magnetic moments. Since the DMI is responsible for various macroscopic properties such as magnetic textures or domain sizes, these results suggest the possibility to tune these properties via the application of external gate voltages.
Keywords: Spintronics, Density Functional Theory, voltage-controlled properties
