Nanoscale mechanics of antiferromagnetic domain walls

Abstract

Antiferromagnets offer remarkable promise for future spintronics devices, where antiferromagnetic order is exploited to encode information [1][2][3]. The control and understanding of antiferromagnetic domain walls (DWs) -the interfaces between domains with differing order parameter orientations -is a key ingredient for advancing such antiferromagnetic spintronics technologies. However, studies of the intrinsic mechanics of individual antiferromagnetic DWs remain elusive since they require sufficiently pure materials and suitable experimental approaches to address DWs on the nanoscale. Here we nucleate isolated, 180 • DWs in a single-crystal of Cr2O3, a prototypical collinear magnetoelectric antiferromagnet, and study their interaction with topographic features fabricated on the sample. We demonstrate DW manipulation through the resulting, engineered energy landscape and show that the observed interaction is governed by the DW's elastic properties. Our results advance the understanding of DW mechanics in antiferromagnets and suggest a novel, topographically defined memory architecture based on antiferromagnetic DWs.

New Dimension in Magnetism and Superconductivity: 3D and Curvilinear Nanoarchitectures

“…[505] The specific example of interplay between the geometry and antiferromagnetic texture illustrating the role of Equation ( 39) is characteristic for the samples with patterned surface, see Figure 12a. This can be effectively combined with the nitrogen vacancy microscopy for imaging individual domain walls in Cr 2 O 3 [22] as well as noncollinear textures in BiFeO 3 . [507] A magnetoelectric collinear antiferromagnet Cr 2 O 3 supports translational domain walls, which have a high mobility in bulk single crystals.…”

“…[507] A magnetoelectric collinear antiferromagnet Cr 2 O 3 supports translational domain walls, which have a high mobility in bulk single crystals. Very recently it is shown a possibility to move them by laser dragging and pin them at the surface by litographically patterned rectangular mesas of width w and thickness t. [22] The domain wall crossing a mesa experiences a distortion, which can be explained by the exchange-driven Neumann boundary conditions for the Néel vector (39) with D 1 = 0. This forces the domain wall plane within the mesa to be perpendicular to its sides and results in the bend of the domain wall plane under the mesa at the characteristic length of about 0.34w, see Figure 12a.…”

“…This forces the domain wall plane within the mesa to be perpendicular to its sides and results in the bend of the domain wall plane under the mesa at the characteristic length of about 0.34w, see Figure 12a. The domain wall shape within the mesa can be described by the ansatz [22] ( , ) 4…”

“…The nontrivial topography of the sample's surface creates an artificial map of pinning centers via the boundary conditions (39). This leads to the formation of curvilinear states of the domain walls at equilibrium, [22] see Figure 12b. The latter ones are of technological interest.…”

“…[14][15][16][17][18] This discussion also tackles the state of the art in modern experimental antiferromagnetism, where the design of the sample topography and boundaries allows to control the domain wall states. [19][20][21][22] With the development of novel fabrication techniques allowing to realize complex 3D architectures, not only the boundary effects but also the extrinsic geometrical properties (e.g., local curvatures) can be addressed rigorously for the case of ferromagnets [23][24][25][26][27] as well as superconductors. [28][29][30] The explored effects are directly related to the interplay between the Traditionally, the primary field, where curvature has been at the heart of research, is the theory of general relativity.…”