Correlation between the Dzyaloshinskii-Moriya interaction and spin-mixing conductance at an antiferromagnet/ferromagnet interface

Abstract

The rich interaction phenomena at antiferromagnet (AFM)/ ferromagnet (FM) interfaces are key ingredients in AFM spintronics, where many underlying mechanisms remain unclear. Here we report a correlation observed between interfacial Dzyaloshinskii-Moriya interaction (DMI) S and effective spin mixing conductance ↑↓ at IrMn/CoFeB interface. Both S and ↑↓ are quantitatively determined with Brillouin light scattering measurements, and increase with IrMn thickness in the range of 2.5~7.5 nm. Such correlation likely originates from the AFM-states-mediated spin-flip transitions in FM, which promote both interfacial DMI and spin pumping effect. Our findings provide deeper insight into the AFM-FM interfacial coupling for future spintronic design.The antiferromagnet (AFM)/ ferromagnet (FM) interfaces are of central importance in the recent development of AFM spintronics [1][2][3][4][5]. Through the interfacial coupling, the unique electric, magnetic and transport properties of the AFM can be bridged to control the FM layer. For instance, the adjacent AFM layer improves the hardness of FM via exchange bias (EB) [6][7][8] or enhances the spin current transport away from FM [9][10][11][12][13]. Taking advantage of the faster dynamics in AFM, one can speed up the optical control of FM by selectively perturbing the spin arrangement of the neighboring AFM layer [5]. An intense and transient torque is subsequently generated onto the FM across the AFM/FM interface [5]. More recently, new strategies utilizing multiple interfacial interactions in synergy lead to promising technology breakthroughs. Examples include the pure electric switching of FM magnetization [1][2][3][4] and the establishment of magnetic skyrmions in AFM/FM systems [14]. Especially, the electric current induced magnetization switching is driven by the spin-orbit torque (SOT) generated in the AFM or at the AFM/FM interface [1, 2,[15][16][17], which also utilizes EB instead of the external magnetic field to break the switching symmetry [1][2][3][4]. In addition, magnetic skyrmion phase has been stabilized at room temperature in AFM/FM systems [14], resulting from the interplay with Dzyaloshinskii-Moriya interaction (DMI), interfacial magnetic anisotropy and EB. The directional motion of such Né el-type magnetic skyrmions can also be efficiently manipulated with the SOT in AFM/FM systems [14].Among the rich interactions at AFM/FM interface, the recently observed interfacial DMI remains most puzzling. While such DMI at AFM/FM interface also promotes noncollinear spin alignments, it exhibits important difference from that in heavy metal (HM)/FM bilayers investigated extensively in recent years [18][19][20][21][22]. Notably, the DMI at IrMn/CoFeB

Direct observation of unusual interfacial Dzyaloshinskii-Moriya interaction in graphene/NiFe/Ta heterostructures

“…Figure 4(d), shows a plot of D s with spin-mixing conductance g ↑↓ , which clearly shows this correlation. This correlation, which is already established in the FM/HM system [18] and antiferromagnet (AFM)/FM system [25] further supports our claim that defect induced extrinsic spin-orbit coupling at the interface is the primary origin of iDMI in our system.…”

“…In addition, it can improve domain wall velocities by suppressing Walker breakdown in magnetic racetrack memory devices and lead to non-reciprocal spin-wave propagation leading towards applications in the high-speed spin-wave logic device [13]. Recently, the direct observation of iDMI has been evidenced mainly in HM/FM/oxide heterostructures [14][15][16][17][18][19][20][21][22][23][24][25].…”

Spin pumping and inverse spin Hall effect in CoFeB/IrMn heterostructures

“…The g ↑↓ r values for S2-S6 found to be 0.606, 0.690, 0.704, 0.696, 0.687 nm −2 . It is also to be noted that our g ↑↓ r values are one order less than the previously reported values with IrMn [10,17,20,41]. The relatively lower value of g ↑↓ r confirms that the spin current flow efficiency is not so good in our heterostructures.…”

“…Most of the ISHE works on IrMn have been performed with crystalline FM materials like Py [15][16][17]. There are very few reports of spin pumping with CoFeB/IrMn bilayers [18][19][20]. The preivous works lag systematic ISHE analysis.…”

Applications of nanomagnets as dynamical systems: II

“…It depends on filling of 5d orbitals (electronegativity) in half-metals (HM) [449]. DMI is driven by spin-flip transitions between 3d states (in the FM) involving intermediate states (from the adjacent layer) with strong SOC strength [236] and is correlated with spinmixing conductance.…”