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Patankar, Shreyas; Hinton, James P.; Griesmar, J.; Orenstein, Joseph; Dodge, J. Steven; Kou, Xufeng; Pan, Lei; Wang, Kang L.; Bestwick, Andrew; Fox, Eli; Goldhaber‐Gordon, David; Wang, Jing; Zhang, Shou Cheng

doi:10.1103/physrevb.92.214440

Cited by 8 publications

(5 citation statements)

References 39 publications

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“…We applied 6 T to align the magnetic domain first and then performed the Faraday rotation measurement by reducing the field from 4 to 0 T. The resonance-enhanced  F ′ is 0.3 rad at 4 T, which is around 40 times larger than that in the recent study on metallic Mn 3 Sn films (40). The gap-induced resonance feature in optical rotations was also recently observed in a magnetic topological insulator (41). The resonanceenhanced terahertz Faraday rotation described here may represent an entirely new phenomenon in the world of the Kondo insulator, which was not observed in SmB 6 (42).…”

Section: Resonance-enhanced Terahertz Faraday Rotationmentioning

confidence: 74%

Kondo physics in antiferromagnetic Weyl semimetal Mn _{3+
x} Sn _{1−
x} films

et al. 2020

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Topology and strong electron correlations are crucial ingredients in emerging quantum materials, yet their intersection in experimental systems has been relatively limited to date. Strongly correlated Weyl semimetals, particularly when magnetism is incorporated, offer a unique and fertile platform to explore emergent phenomena in novel topological matter and topological spintronics. The antiferromagnetic Weyl semimetal Mn3Sn exhibits many exotic physical properties such as a large spontaneous Hall effect and has recently attracted intense interest. In this work, we report synthesis of epitaxial Mn3+xSn1−x films with greatly extended compositional range in comparison with that of bulk samples. As Sn atoms are replaced by magnetic Mn atoms, the Kondo effect, which is a celebrated example of strong correlations, emerges, develops coherence, and induces a hybridization energy gap. The magnetic doping and gap opening lead to rich extraordinary properties, as exemplified by the prominent DC Hall effects and resonance-enhanced terahertz Faraday rotation.

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Section: Resonance-enhanced Terahertz Faraday Rotationmentioning

confidence: 74%

Kondo physics in antiferromagnetic Weyl semimetal Mn _{3+
x} Sn _{1−
x} films

et al. 2020

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“…In a polar Kerr measurement, linearly polarized light was focused onto the sample with a ~10 µm diameter spot by a reflective objective with an incidence angle close to normal and the reflected light was collected by a pick-up mirror. To measure the Kerr rotation, we used a technique based on a photoelastic optical phase modulator (PEM) 41, 42 . Synchronous detection of the reflected light at the second harmonic of the PEM frequency and DC reflectivity enabled precision of rotation with 0.25 milli-degrees (5 µrad) sensitivity.…”

Section: Methodsmentioning

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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“…A reflective microscope objective was used to avoid unwanted Faraday rotation from glass optics [30]. Illumination was provided by a HeNe laser, with a photon energy ( ω = 1.96 eV) in the vicinity of a known resonance in the MOKE spectrum of similar materials [31]. For simultaneous resistance, AHE, and MOKE hysteresis measurements, the laser spot was positioned on an unconnected leg of the Hall bar to avoid optical effects on the transport measurements.…”

Section: Methodsmentioning

confidence: 99%

Local optical control of ferromagnetism and chemical potential in a topological insulator

Yeats

Mintun

Pan

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Many proposed experiments involving topological insulators (TIs) require spatial control over time-reversal symmetry and chemical potential. We demonstrate reconfigurable micron-scale optical control of both magnetization (which breaks time-reversal symmetry) and chemical potential in ferromagnetic thin films of Cr-(Bi,Sb) 2 Te 3 grown on SrTiO 3 . By optically modulating the coercivity of the films, we write and erase arbitrary patterns in their remanent magnetization, which we then image with Kerr microscopy. Additionally, by optically manipulating a space charge layer in the underlying SrTiO 3 substrates, we control the local chemical potential of the films. This optical gating effect allows us to write and erase p-n junctions in the films, which we study with photocurrent microscopy. Both effects are persistent and may be patterned and imaged independently on a few-micron scale. Dynamic optical control over both magnetization and chemical potential of a TI may be useful in efforts to understand and control the edge states predicted at magnetic domain walls in quantum anomalous Hall insulators.topological insulators | ferromagnetism | Kerr microscopy | magneto-optical recording | photocurrent microscopy T he unusual topology of electronic bands in some materials can produce quantum states that are stabilized by symmetry. Topological insulators (TIs) have attracted particular attention for their symmetry-protected surface and edge states, which may hold promise for applications in spintronics and quantum computing (1, 2). Ferromagnetic TIs combine a topologically nontrivial band structure with ferromagnetism, which intrinsically breaks time-reversal symmetry (TRS) and therefore may produce unusual electromagnetic phenomena such as the topological magnetoelectric effect (3, 4), quantized Kerr and Faraday rotation (5, 6), and quantization of the anomalous Hall effect (QAHE) (7,8). However, while the quantum states in an ideal TI are protected by symmetry, most topologically nontrivial materials have proven difficult to grow and engineer. In particular, residual bulk conductivity, and the tendency of TI materials to degrade during semiconductor processing, have impeded many experimental efforts (9-11). Harnessing the unique physics of these materials will require better understanding and control of their magnetism and disorder, as well as methods to engineer TI devices without degrading the properties that make these materials unique.A major challenge in TI research is to identify systems in which the energies and symmetries of TI physics can be reliably controlled in the laboratory. For instance, a criterion for the QAH insulator state is for the chemical potential of electrons µ to lie within an energy gap ∆ in the surface state dispersion, where ∆ ∝ | M ·n|, M is the local magnetization andn is the surface normal (1, 2). At the edges of a uniformly magnetized film, the top and bottom surfaces meet and therefore M ·n changes sign, causing ∆ to vanish. In sufficiently thin films, the vanishing gap produces 1D co...

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Resonant magneto-optic Kerr effect in the magnetic topological insulatorCr:(Sbx,Bi1−x)2Te

Cited by 8 publications

References 39 publications

Kondo physics in antiferromagnetic Weyl semimetal Mn _{3+
x} Sn _{1−
x} films

Kondo physics in antiferromagnetic Weyl semimetal Mn _{3+
x} Sn _{1−
x} films

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

Local optical control of ferromagnetism and chemical potential in a topological insulator

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Resonant magneto-optic Kerr effect in the magnetic topological insulatorCr:(Sbx,Bi1−x)2Te

Cited by 8 publications

References 39 publications

Kondo physics in antiferromagnetic Weyl semimetal Mn 3+ x Sn 1− x films

Kondo physics in antiferromagnetic Weyl semimetal Mn 3+ x Sn 1− x films

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

Local optical control of ferromagnetism and chemical potential in a topological insulator

Contact Info

Product

Resources

About

Kondo physics in antiferromagnetic Weyl semimetal Mn _{3+
x} Sn _{1−
x} films

Kondo physics in antiferromagnetic Weyl semimetal Mn _{3+
x} Sn _{1−
x} films