Ruderman\u2013Kittel\u2013Kasuya\u2013Yosida-type interfacial Dzyaloshinskii\u2013Moriya interaction in heavy metal/ferromagnet heterostructures

Taehyun Kim,Gyu Won Kim,Yong Jin Kim,Andrey Stashkevich,In Ho Cha,Young Keun Kim,Alexander S Samardak,Mohamed Belmeguenai,Salim M Chérif,Yves Roussigné

doi:10.1038/s41467-021-23586-y

Abstract

The manipulation of magnetization with interfacial modification using various spin-orbit coupling phenomena has been recently revisited due to its scientific and technological potential for next-generation memory devices. Herein, we experimentally and theoretically demonstrate the interfacial Dzyaloshinskii–Moriya interaction characteristics penetrating through a MgO dielectric layer inserted between the Pt and CoFeSiB. The inserted MgO layer seems to function as a chiral exchange interaction mediator of the interfacial Dzyaloshinskii–Moriya interaction from the heavy metal atoms to ferromagnet ones. The potential physical mechanism of the anti-symmetric exchange is based on the tunneling-like behavior of conduction electrons through the semi-conductor-like ultrathin MgO. Such behavior can be correlated with the oscillations of the indirect exchange coupling of the Ruderman–Kittel–Kasuya–Yosida type. From the theoretical demonstration, we could provide approximate estimation and show qualitative trends peculiar to the system under investigation.

Highlights

The manipulation of magnetization with interfacial modification using various spin-orbit coupling phenomena has been recently revisited due to its scientific and technological potential for next-generation memory devices
The addition of the MgO spacer layer between the heavy metal (HM) and FM did not abruptly decrease the interfacial Dzyaloshinskii–Moriya interaction (iDMI) energy density; instead, it drops down slowly in a non-monotonic fashion resembling the oscillations in the case of RKKY coupling of two FM films through a nonmagnetic spacer until tMgO reached 2.1 nm
We have addressed a fundamental issue of the role of a nonmetallic MgO spacer as a conveyor of iDMI between FM and HM layers and the physics behind it

Summary

Introduction

The manipulation of magnetization with interfacial modification using various spin-orbit coupling phenomena has been recently revisited due to its scientific and technological potential for next-generation memory devices. The potential physical mechanism of the anti-symmetric exchange is based on the tunneling-like behavior of conduction electrons through the semi-conductor-like ultrathin MgO. Such behavior can be correlated with the oscillations of the indirect exchange coupling of the Ruderman–Kittel–Kasuya–Yosida type. An elementary iDMI cell referred to as a Fert’s triangle[12] is considered as a triangle comprised of two magnetic atoms on the ferromagnet (FM) side linked to each other via a SOC-carrying atom on the HM side through the exchange mechanism. In both mechanisms, the presence of SOC and symmetry reduction is instrumental[13]

Methods

Results

Conclusion