Magnetostatic twists in room-temperature skyrmions explored by nitrogen-vacancy center spin texture reconstruction

Dovzhenko, Yuliya; Casola, Francesco; Schlotter, Sarah; Zhou, Tony; Büttner, Felix; Walsworth, Ronald L.; Beach, Geoffrey S. D.; Yacoby, Amir

doi:10.1038/s41467-018-05158-9

Cited by 190 publications

(178 citation statements)

References 35 publications

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“…Since a skyrmion has a large number of flipped spins, one can sense a trapped skyrmion in an impurity potential via spin-polarized STM, or local magnetometers like a scanning nano-squid [75] or a Nitrogen-Vacancy (NV) center [76]. Finally, if the state is indeed an AFM, then applying a strong B ⊥ will cant the spins and change the ground state.…”

Section: Discussionmentioning

confidence: 99%

Symmetry breaking and skyrmionic transport in twisted bilayer graphene

2020

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Motivated by recent low-temperature magnetoresistance measurements in twisted bilayer graphene aligned with hexagonal Boron Nitride substrate, we perform a systematic study of possible symmetry breaking orders in this device at a filling of two electrons per Moiré unit cell. We find that the surprising non-monotonic dependence of the resistance on an out-of-plane magnetic field is difficult to reconcile with particle-hole charge carriers from the low-energy bands in symmetry broken phases. We invoke the non-zero Chern numbers of the twisted bilayer graphene flat bands to argue that skyrmion textures provide an alternative for the dominant charge carriers. Via an effective field-theory for the spin degrees of freedom, we show that the effect of spin Zeeman splitting on the skyrmion excitations provides a possible explanation for the non-monotonic magnetoresistance. We suggest several experimental tests, including the functional dependence of the activation gap on the magnetic field, for our proposed correlated insulating states at different integer fillings. We also discuss possible exotic phases and quantum phase transitions that can arise via skyrmion-pairing on doping such an insulator. arXiv:1908.00986v1 [cond-mat.str-el]

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Section: Discussionmentioning

confidence: 99%

Symmetry breaking and skyrmionic transport in twisted bilayer graphene

2020

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“…33 By recording the magnetic field along the NV axis produced by the magnetization pattern in the film, all three components of the magnetic field were reconstructed. 34 This technique allows one to obtain the underlying spin texture from a map of the magnetic field, 34 so it may serve as an alternative way to determine the direction of the magnetization at the domain wall center.…”

Section: Discussionmentioning

confidence: 99%

Quantum control of topological defects in magnetic systems

Takei

Mohseni

2018

Phys. Rev. B

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Energy-efficient classical information processing and storage based on topological defects in magnetic systems have been studied over past decade. In this work, we introduce a class of macroscopic quantum devices in which a quantum state is stored in a topological defect of a magnetic insulator. We propose non-invasive methods to coherently control and readout the quantum state using ac magnetic fields and magnetic force microscopy, respectively. This macroscopic quantum spintronic device realizes the magnetic analog of the threelevel rf-SQUID qubit and is built fully out of electrical insulators with no mobile electrons, thus eliminating decoherence due to the coupling of the quantum variable to an electronic continuum and energy dissipation due to Joule heating. For a domain wall sizes of 10 − 100 nm and reasonable material parameters, we estimate qubit operating temperatures in the range of 0.1 − 1 K, a decoherence time of about 0.01 − 1 µs, and the number of Rabi flops within the coherence time scale in the range of 10 2 − 10 4 .

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“…Hence, it confirms by a direct measurement and without assumptions, that the DW texture is Néel (CW or CCW) as already known for this multilayer system with additive interfacial DM interaction either indirectly through analysis of the skyrmion size and comparison with micromagnetic simulations [15] or directly through Lorentz transmission electron microscopy [27]. Other methods have already been utilized to access to the texture of the DW or skyrmions such as spin-polarized STM [1,28], scanning nitrogen-vacancies-magnetometry (NV) [29,30] or spinpolarized low-energy electron microscopy (SPLEEM) [31]. On the other hand, DM interaction has also been probed by spin wave spectroscopy techniques such as Brillouin light scattering (BLS) [32] or time-resolved Kerr microscopy [33].…”

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confidence: 99%

Chirality in Magnetic Multilayers Probed by the Symmetry and the Amplitude of Dichroism in X-Ray Resonant Magnetic Scattering

et al. 2018

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Chirality is central to understand many fundamental mechanisms in various domains of physics and chemistry. In condensed matter, a large variety of physical phenomena hinge on the emergence of these complex chiral windings of order parameters, their observation and subsequently their control especially in magnetism and spintransport at the nanoscale. The ability to probe the nature of these chiral magnetic textures has now become a crucial element of modern magnetism and is therefore essential to gain a deeper understanding of these mechanisms. Spin-polarized scanning tunneling microscopy (SP-STM) revealed that magnetic textures with a cycloidal configuration of the magnetization and Néel domain walls are stabilized in ultra-thin magnetic films (one or a few atomic layers) on heavy metal substrates [1] . It was realized that these magnetic textures are stabilized by Dzyaloshinskii-Moriya (DM) interaction [2,3], (∑ 〈 〉• × , with Si and Sj two neighboring spins) which is the anti-symmetric analog of the Heisenberg interaction favoring a curling magnetization textures around the DM vector . The DM interaction requires spin-orbit coupling (SOC) and broken inversion symmetry, found either in specific crystalline structures, such as B20 materials [4], or at film interfaces [5,6].In this letter, we demonstrate that XRMS experiments (Figure 1a) allow us to reveal the actual magnetic textures existing in ultrathin magnetic multilayers with perpendicular anisotropy and large interfacial chiral interaction. Importantly, this determination is straightforward and does not require any assumptions or careful comparison to parameter-dependent micromagnetic simulations. Moreover, the circular dichroism in XMRS enables to identify directly not only the direction but also the sense of the magnetic winding and therefore of the actual sign of DM interaction as we proved by a thorough analysis. This information has a far-reaching impact in particular for spin-orbitronics and spin-orbit torque (SOT) studies. Indeed, SOT is a recent very promising approach to move efficiently domain walls [7] and magnetic skyrmions along magnetic race-tracks and shows therefore a great potential for future spintronic devices. Yet, the detailed texture of the domain walls plays a major role in their motion [8]: the DW high speed is related to its nature (Néel or Bloch) while its direction of motion depends on its chirality [7]. Besides, DM interaction can play an important role for existing technological applications in spintronics already using ultrathin magnetic multilayers with perpendicular magnetic anisotropy such as MRAM or detectors, in which the presence and the impact of non-negligible DM interaction has been largely overlooked (see e.g. [9,10]), emphasizing thus the need to probe its consequences on magnetic textures. XRMS presents several advantages that might soon turn it to a standard way to characterize and quantify the DM interaction. First, XMRS is a non-perturbative technique contrary to the approach based on magnetic domain analysis th...

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Magnetostatic twists in room-temperature skyrmions explored by nitrogen-vacancy center spin texture reconstruction

Cited by 190 publications

References 35 publications

Symmetry breaking and skyrmionic transport in twisted bilayer graphene

Symmetry breaking and skyrmionic transport in twisted bilayer graphene

Quantum control of topological defects in magnetic systems

Chirality in Magnetic Multilayers Probed by the Symmetry and the Amplitude of Dichroism in X-Ray Resonant Magnetic Scattering

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