Large spontaneous Hall effects in chiral topological magnets

Nakatsuji, Satoru; Higo, Tomoya; Ikhlas, Muhammad; Tomita, Takahiro; Tian, Zhaoming

doi:10.1080/14786435.2017.1352106

Cited by 8 publications

(5 citation statements)

References 68 publications

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“…Here we focus particularly on Mn 3 Sn which involve both Weyl physics [22,23] and antiferromagnetism with large Néel temperature of T N ∼420 K [24]. In Mn 3 Sn magneto-geometrical frustration in the Kagome lattice leads to non-collinear antiferromagnetic order causing Mn moments to lie in the ab-plane (Kagome-plane) with moments aligned at 120 0 with each other.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of spin diffusion length and spin Hall angle of the antiferromagnetic Weyl semimetal Mn3Sn

et al. 2019

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Antiferromagnetic Weyl semimetal Mn3Sn has shown to generate strong intrinsic anomalous Hall effect (AHE) at room temperature, due to large momentum-space Berry curvature from the timereversal symmetry breaking electronic bands of the Kagome planes. This prompts us to investigate intrinsic spin Hall effect, a transverse phenomenon with identical origin as the intrinsic AHE. We report inverse spin Hall effect experiments in nanocrystalline Mn3Sn nanowires at room temperature using spin absorption method which enables us to quantitatively derive both the spin diffusion length and the spin Hall angle in the same device. We observed clear absorption of the spin current in the Mn3Sn nanowires when kept in contact with the spin transport channel of a lateral spin-valve device. We estimate spin diffusion length λ s(M n 3 Sn) ∼0.75 ±0.67 nm from the comparison of spin signal of an identical reference lateral spin valve without Mn3Sn nanowire. From inverse spin Hall measurements, we evaluate spin Hall angle θSH ∼5.3 ± 2.4 % and spin Hall conductivity σSH ∼46.9 ± 3.4 (h/e) (Ω cm) −1 . The estimated spin Hall conductivity agrees with both in sign and magnitude to the theoretically predicted intrinsic σ int SH ∼36-96 (h/e) (Ω cm) −1 . We also observed anomalous Hall effect at room temperature in nano-Hall bars prepared at the same time as the spin Hall devices. Large anomalous Hall conductivity along with adequate spin Hall conductivity makes Mn3Sn a promising material for ultrafast and ultrahigh-density spintronics devices.

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Section: Introductionmentioning

confidence: 99%

Evaluation of spin diffusion length and spin Hall angle of the antiferromagnetic Weyl semimetal Mn3Sn

et al. 2019

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“…On the other hand, recent theoretical and experimental progress has revealed that systems such as certain spin liquids and non-collinear antiferromagnets may exhibit a large Hall response in zero applied magnetic field (anomalous Hall effect or AHE) despite a vanishing magnetization 15,[24][25][26][27][28][29][30][31] . Because the AHE has the same symmetry requirements as the MOKE 32 , it is possible that the same class of antiferromagnets may exhibit a Kerr rotation.…”

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confidence: 99%

Large magneto-optical Kerr effect and imaging of magnetic octupole domains in an antiferromagnetic metal

et al. 2018

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When a polarized light beam is incident upon the surface of a magnetic material, the reflected light undergoes a polarization rotation1. This magneto-optical Kerr effect (MOKE) has been intensively studied in a variety of ferro- and ferrimagnetic materials because it provides a powerful probe for electronic and magnetic properties2, 3 as well as for various applications including magneto-optical recording4. Recently, there has been a surge of interest in antiferromagnets (AFMs) as prospective spintronic materials for high-density and ultrafast memory devices, owing to their vanishingly small stray field and orders of magnitude faster spin dynamics compared to their ferromagnetic counterparts5–9. In fact, the MOKE has proven useful for the study and application of the antiferromagnetic (AF) state. Although limited to insulators, certain types of AFMs are known to exhibit a large MOKE, as they are weak ferromagnets due to canting of the otherwise collinear spin structure10–14. Here we report the first observation of a large MOKE signal in an AF metal at room temperature. In particular, we find that despite a vanishingly small magnetization of M ~0.002 µB/Mn, the non-collinear AF metal Mn3Sn15 exhibits a large zero-field MOKE with a polar Kerr rotation angle of 20 milli-degrees, comparable to ferromagnetic metals. Our first-principles calculations have clarified that ferroic ordering of magnetic octupoles in the non-collinear Néel state16 may cause a large MOKE even in its fully compensated AF state without spin magnetization. This large MOKE further allows imaging of the magnetic octupole domains and their reversal induced by magnetic field. The observation of a large MOKE in an AF metal should open new avenues for the study of domain dynamics as well as spintronics using AFMs.

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“…Non-collinear antiferromagnets such as Mn 3 Sn and Mn 3 Ge have recently emerged as a fascinating class of materials that can exhibit a large anomalous Hall effect (AHE) despite having a negligibly small net magnetic moment [1][2][3][4][5][6]. The AHE can arise in these and related antiferromagnetic (AF) materials when the underlying spin order not only breaks time-reversal symmetry but also lacks additional spatial symmetries that would otherwise force the AHE to vanish.…”

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Comparing the anomalous Hall effect and the magneto-optical Kerr effect through antiferromagnetic phase transitions in Mn3Sn

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Sung

Thomas

et al. 2019

Applied Physics Letters

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In the non-collinear antiferromagnet Mn3Sn, we compare simultaneous measurements of the anomalous Hall effect (AHE) and the magneto-optical Kerr effect (MOKE) through two magnetic phase transitions: the high-temperature paramagnetic/antiferromagnetic phase transition at the Néel temperature (TN ≈420 K), and a lower-temperature incommensurate magnetic ordering at T1 ≈270 K. While both the AHE and MOKE are sensitive to the same underlying symmetries of the antiferromagnetic non-collinear spin order, we find that the transition temperatures measured by these two techniques unexpectedly differ by approximately 10 K. Moreover, the applied magnetic field at which the antiferromagnetic order reverses is significantly larger when measured by MOKE than when measured by AHE. These results point to a difference between the bulk and surface magnetic properties of Mn3Sn.

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Large spontaneous Hall effects in chiral topological magnets

Cited by 8 publications

References 68 publications

Evaluation of spin diffusion length and spin Hall angle of the antiferromagnetic Weyl semimetal Mn3Sn

Evaluation of spin diffusion length and spin Hall angle of the antiferromagnetic Weyl semimetal Mn3Sn

Large magneto-optical Kerr effect and imaging of magnetic octupole domains in an antiferromagnetic metal

Comparing the anomalous Hall effect and the magneto-optical Kerr effect through antiferromagnetic phase transitions in Mn3Sn

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