Anomalous Anisotropic Magnetoresistance of Antiferromagnetic Epitaxial Bimetallic Films: Mn₂Au and Mn₂Au/Fe Bilayers

Abstract

wileyonlinelibrary.comtraditional wholly ferromagnetic (FM) spintronic devices. [1][2][3] The reduced stray fi elds and faster spin dynamics of antiferomagnitic elements would allow further miniaturization with less cross-talk leading to faster higher density memory. The fast-evolving fi eld of antiferromagnetic spintronics is being pursued on many fronts, Núñez et al. studied spin torque and giant magnetoresistance (MR) in antiferromagnetic metals, [ 4 ] Hals et al. derived a phenomenological theory for current-induced dynamics in antiferromagnets, [ 5 ] and Shvets et al. [ 6 ] and Chshiev and co-workers [ 7 ] discussed the use of an antiferromagnetic dielectric layer as a tunneling barrier. More recently theoretical studies have been supported and complemented by steady experimental progress, the antiferromagnetic material IrMn has been utilized in demonstrating the possibility of producing a 100% spin-valve-like signal in an IrMnbased tunnel junction [ 8 ] and in the electrical measurement of antiferromagnetic moments in IrMn/NiFe stacks. [ 9 ] Lately, signifi cant strides have been made showing the practicality and versatility of antiferromagnetic spintronics. Pan and co-workers Recently intensive efforts have been devoted to the emerging fi eld of antiferromagnetic (AFM) spintronics, where ferromagnetic electrodes are substituted by antiferromagnets. This study investigates the anisotropic magnetoresistance (AMR) of epitaxial tetragonal antiferromagnetic bimetallic fi lms: Mn 2 Au and Mn 2 Au/Fe bilayers. An anomalous AMR effect with additional peaks is observed. This study theoretically and experimentally demonstrates that the AFM spins of Mn 2 Au can be viewed and controlled at room temperature, and this is achievable with a notably relatively small magnetic fi eld of 200 mT. Strong hybridization between Au and Mn, and strong modifi cation of the intrinsic quadratic anisotropy of Mn 2 Au from interfacial biquadratic anisotropy result in an additional anomalous AMR component of 1%. The fi ndings suggest that Mn 2 Au fi lms can be used in room temperature antiferromagnetic spintronics.

Giant spin torque efficiency in single-crystalline antiferromagnet Mn2Au films

“…As shown in the inset in Fig. 3b, the dual in-plane magnetic easy axes results are well in line with the predicted magnetic structure of the (002)oriented single-crystal Mn 2 Au [20,21,35]. By carrying out the in-plane harmonic Hall voltage response measurement in a reference sample with the structure of STO substrate/Mn 2 Au (25 nm)/Cu (1 nm)/Py (10 nm)/SiO 2 (4 nm), as shown in the Fig.…”

“…Among potential AFM materials, the collinear Mn 2 Au material has a great possibility of providing large ξ DL since the gold atoms result in a strong spin-orbit coupling (SOC) [19,20]. Regarding previous studies on the ξ DL of Mn 2 Au film, Singh et al [21] reported a large ξ DL = 0.22 in a Mn 2 Au/CoFeB bilayer system.…”

Strong Orientation-Dependent Spin-Orbit Torque in Thin Films of the Antiferromagnet Mn2Au

“…Compared to polycrystalline Mn 2 Au films grown by molecular beam epitaxy [29,30] and partially (001)-oriented Mn 2 Au films deposited by sputtering [31], experiments below attain quasi-epitaxial (103), (101) and (204) Mn 2 Au films, and demonstrate the orientation dependent Néel-order spin-orbit torque switching in single layer Mn 2 Au films with different switching features for different orientations.…”

Antiferromagnet‐Based Spintronic Functionality by Controlling Isospin Domains in a Layered Perovskite Iridate

“…The main issue to generate functional spin transport based on antiferromagnets is to manipulate and detect an AFM state. The AFM memory state has been examined in several studies using anisotropic magnetoresistance (AMR); however, it mostly requires complicated stacking geometry for unified spintronic functionality. Since the AFM metallic alloys were mostly adopted for the desired functionality, AMR effects in ohmic magnetic devices are ordinarily restricted to variation of a few percent, which motivated recent studies focusing on tunneling AMR .…”