Optical Readout of the Néel Vector in the Metallic Antiferromagnet Mn2Au

Abstract

Metallic antiferromagnets with broken inversion symmetry on the two sublattices, strong spin-orbit coupling, and high Néel temperatures offer alternative opportunities for applications in spintronics. Especially Mn 2 Au, with a high Néel temperature and high conductivity, is particularly interesting for real-world applications. Here, manipulation of the orientation of the staggered magnetization, (i.e., the Néel vector) by current pulses was recently demonstrated, with the readout limited to studies of anisotropic magnetoresistance or x-ray magnetic linear dichroism. Here we report on the in-plane reflectivity anisotropy of Mn 2 Au(001) films, which are Néel vector aligned in pulsed magnetic fields. In the near-infrared region, the anisotropy is approximately 0.6%, with higher reflectivity for the light polarized along the Néel vector. The observed magnetic linear dichroism is about 4 times larger than the anisotropic magnetoresistance. This suggests the dichroism in Mn 2 Au is a result of the strong spin-orbit interactions giving rise to anisotropy of interband optical transitions, which is in line with recent studies of electronic band structure. The considerable magnetic linear dichroism in the near-infrared region could be used for ultrafast optical readout of the Néel vector in Mn 2 Au.

Direct Observation of Antiferromagnetic Parity Violation in the Electronic Structure of Mn$_2$Au

“…In photoemission spectroscopy a similar effect can be observed [23]. X-ray magnetic linear dichroism photoemission electron microscopy (XMLD-PEEM) was successfully used to observe AFM domains in a wide range of materials [23][24][25][26][27], including both CuMnAs [10,28] and Mn 2 Au thin films [16,29].…”

Emergent phase transition in Cluster Ising model with dissipation

“…Therefore, cluster Ising model is put forward as a good toy model to investigate the phase transitions in such quantum many-body systems. Generally, SPT cluster phase can be characterized by global sting order [18,19] while the SB antiferromagnetic (AFM) state can be identified by local staggered magnetization [20,21].…”

Optically-triggered strain-driven Néel vector manipulation in a metallic antiferromagnet

“…All these properties could enable high information density, with the direction of the staggered magnetization (Néel vector, L) as the information carrier. The lack of sensitivity to external magnetic fields, however, poses challenges in terms of writing [5][6][7] and read-out [7][8][9][10][11] schemes. Exploring the ways to rapidly and reliably manipulate the Néel vector direction is at the heart of the current AFM spintronics research.…”

“…Several approaches for switching the direction of the Néel vector have been suggested, which include aligning the Néel vector by high magnetic fields, 13, 14 application of strain, 15,16 and, most prominently, using current-driven Néel spin-orbit torques. [5][6][7] In terms of the read-out, in addition to X-ray magnetic linear dichroism, 13,16,17 electrical read-out via the anisotropic magnetoresistance (AMR) 5, 7 and optical magnetic linear dichroism (OMLD) 10,18 have been realized. In spite the achieved progress, an ultrafast approach for locally changing the Néel vector orientation is needed to fully exploit the potential of AFMs in spintronics.…”

“…The demonstrated method of local optical manipulation of the Néel vector can be applied to a range of collinear AFMs with low magneto-crystalline anisotropies, enabling ultrafast writing of magnetically stored information. In combination with fast optical readout schemes, 10,18 this approach provides means for studying switching and domain wall dynamics on an ultrafast timescale.…”