An official website of the United States government
Noncollinear antiferromagnet Mn3Sn has attracted wide interest as it is a candidate for Weyl semimetal. Here, we report the observation of topological Hall like signals in Mn3Sn/Pt bilayers grown on Al2O3(0001). X-ray diffraction and scanning transmission electron microscopy results confirm the high epitaxial quality of the c-axis-oriented Mn3Sn films. The detected topological Hall resistivity shows a broad temperature range from 210 to 365 K by tuning the thickness of Mn3Sn from 3 to 15 nm. Compared with previously reported topological Hall effects in Mn3Sn at temperatures below 50 K, the observed high-temperature topological Hall signal is likely due to the stabilization of topological spin textures enabled by the strong spin–orbit coupling of the Pt overlayer and the Dzyaloshinskii–Moriya interaction at the Mn3Sn/Pt interface.
more »
« less
Large spin to charge conversion in antiferromagnetic Weyl semimetal Mn3Sn
The Weyl antiferromagnet Mn3Sn has recently attracted significant attention as it is not only a novel magnetic quantum material of fundamental interest, but it also opens opportunities to investigate a number of exotic spin-dependent transports for practical antiferromagnetic devices. Here, we report the large spin to charge conversion observed in YIG/Mn3Sn. Evidenced by both spin Seebeck and spin pumping measurements, the spin to charge conversion efficiency of Mn3Sn is found ∼2.5 times of that for the conventional heavy metal Ta. Our results suggest a promising potential for employing a topological non-trivial antiferromagnet to achieve more efficient spin to charge conversion than conventional metallic materials.
more »
« less
- Award ID(s):
- 1935362
- PAR ID:
- 10594650
- Publisher / Repository:
- American Institute of Physics
- Date Published:
- Journal Name:
- APL Materials
- Volume:
- 9
- Issue:
- 4
- ISSN:
- 2166-532X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Noncollinear antiferromagnets with novel magnetic orders, vanishingly small net magnetization and exotic spin related properties hold enormous promise for developing next generation, transformative spintronic applications. A major ongoing research focus of this community is to explore, control, and harness unconventional magnetic phases of this emergent material system to deliver state-of-the-art functionalities for modern microelectronics. Here we report direct imaging of magnetic domains of polycrystalline Mn3Sn films, a prototypical noncollinear antiferromagnet, using nitrogen-vacancy-based single-spin scanning microscopy. Nanoscale evolution of local stray field patterns of Mn3Sn samples are systematically investigated in response to external driving forces, revealing the characteristic “heterogeneous” magnetic switching behaviors in polycrystalline textured Mn3Sn films. Our results contribute to a comprehensive understanding of inhomogeneous magnetic orders of noncollinear antiferromagnets, highlighting the potential of nitrogen-vacancy centers to study microscopic spin properties of a broad range of emergent condensed matter systems.more » « less
-
Mn 3 Sn, a metallic antiferromagnet with an anti-chiral 120° spin structure, generates intriguing magneto-transport signatures such as a large anomalous Hall effect, spin-polarized current with novel symmetries, anomalous Nernst effect, and magneto-optic Kerr effect. When grown epitaxially as MgO(110)[001]∥Mn3Sn(01¯1¯0)[0001], Mn3Sn experiences a uniaxial tensile strain, which changes the bulk sixfold anisotropy to a twofold perpendicular magnetic anisotropy (PMA). Here, we investigate the field-assisted spin–orbit-torque (SOT)-driven dynamics in single-domain Mn3Sn with PMA. We find that for non-zero external magnetic fields, the magnetic octupole moment of Mn3Sn can be switched between the two stable states if the input current is between two field-dependent critical currents. Below the lower critical current, the magnetic octupole moment exhibits a stationary state in the vicinity of the initial stable state. On the other hand, above the higher critical current, the magnetic octupole moment shows oscillatory dynamics which could, in principle, be tuned from the 100s of megahertz to the terahertz range. We obtain approximate analytic expressions of the two critical currents that agree very well with the numerical simulations for experimentally relevant magnetic fields. We also obtain a unified functional form of the switching time vs the input current for different magnetic fields. Finally, we show that for lower values of Gilbert damping (α≲2×10−3), the critical currents and the final steady states depend significantly on α. The numerical and analytic results presented in our work can be used by both theorists and experimentalists to understand the SOT-driven order dynamics in PMA Mn3Sn and design future experiments and devices.more » « less
-
Novel noncollinear antiferromagnets with spontaneous time-reversal symmetry breaking, nontrivial band topology, and unconventional transport properties have received immense research interest over the past decade due to their rich physics and enormous promise in technological applications. One of the central focuses in this emerging field is exploring the relationship between the microscopic magnetic structure and exotic material properties. Here, the nanoscale imaging of both spin-orbit-torque-induced deterministic magnetic switching and chiral spin rotation in noncollinear antiferromagnet Mn3Sn films using nitrogen-vacancy (NV) centers is reported. Direct evidence of the off-resonance dipole-dipole coupling between the spin dynamics in Mn3Sn and proximate NV centers is also demonstrated with NV relaxometry measurements. These results demonstrate the unique capabilities of NV centers in accessing the local information of the magnetic order and dynamics in these emergent quantum materials and suggest new opportunities for investigating the interplay between topology and magnetism in a broad range of topological magnets.more » « less
-
We numerically investigate and develop analytic models for both the DC and pulsed spin–orbit-torque (SOT)-driven response of order parameter in single-domain Mn3Sn, which is a metallic antiferromagnet with an anti-chiral 120° spin structure. We show that DC currents above a critical threshold can excite oscillatory dynamics of the order parameter in the gigahertz to terahertz frequency spectrum. Detailed models of the oscillation frequency vs input current are developed and found to be in excellent agreement with the numerical simulations of the dynamics. In the case of pulsed excitation, the magnetization can be switched from one stable state to any of the other five stable states in the Kagome plane by tuning the duration or the amplitude of the current pulse. Precise functional forms of the final switched state vs the input current are derived, offering crucial insights into the switching dynamics of Mn3Sn. The readout of the magnetic state can be carried out via either the anomalous Hall effect or the recently demonstrated tunneling magnetoresistance in an all-Mn3Sn junction. We also discuss possible disturbance of the magnetic order due to heating that may occur if the sample is subject to large currents. Operating the device in a pulsed mode or using low DC currents reduces the peak temperature rise in the sample due to Joule heating. Our predictive modeling and simulation results can be used by both theorists and experimentalists to explore the interplay of SOT and the order dynamics in Mn3Sn and to further benchmark the device performance.more » « less
