Macroscopic Quantum Tunneling of a Topological Ferromagnet

Fijalkowski, Kajetan M.; Liu, Nan; Mandal, Pankaj Kumar; Schreyeck, S.; Βrunner, Karl; Gould, C.; Molenkamp, Laurens W.

doi:10.1002/advs.202303165

Cited by 3 publications

(3 citation statements)

References 44 publications

(78 reference statements)

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“…A key question to be addressed is to determine the minimum size limit below which the QAH effect breaks down. Recent work has demonstrated that the quantization is well preserved in the deep sub-micrometer size limit [56][57][58]. For example, when the MTI films were patterned into miniaturized Hall bar devices with a sub-µm channel width as shown in Figure 2a, the magnetic hysteresis loop of ρ xx and ρ xy still resembled the behavior in large-scale devices (Figure 2b,c) [56].…”

Section: Scaling Behavior During Quantum Phase Transitions In Finite-...mentioning

confidence: 87%

“…By measuring the temperature, current bias, and gate dependence, the breakdown of the QAH effect in finite-sized MTI samples can be attributed to bulk localized states mediated by the cross-channel back-scattering mechanism [56], as demonstrated in Figure 2d,e. In addition to quantized states, during the magnetic switching, telegraph noises due to magnetic fluctuations are also observed in sub-µm devices, and careful analyses of these noise spectrum give an estimated magnetic domain size of an ~100-200 nm range [56,58]. Whilst the quantization is persistent in quantized states in mesoscopic MTI devices, the scaling behavior shows a strong size dependence in the quantum critical regime during the topological phase transition [62].…”

Section: Scaling Behavior During Quantum Phase Transitions In Finite-...mentioning

confidence: 99%

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Manipulating Topological Phases in Magnetic Topological Insulators

Qiu,

Yang,

Chong

et al. 2023

Nanomaterials

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Magnetic topological insulators (MTIs) are a group of materials that feature topological band structures with concurrent magnetism, which can offer new opportunities for technological advancements in various applications, such as spintronics and quantum computing. The combination of topology and magnetism introduces a rich spectrum of topological phases in MTIs, which can be controllably manipulated by tuning material parameters such as doping profiles, interfacial proximity effect, or external conditions such as pressure and electric field. In this paper, we first review the mainstream MTI material platforms where the quantum anomalous Hall effect can be achieved, along with other exotic topological phases in MTIs. We then focus on highlighting recent developments in modulating topological properties in MTI with finite-size limit, pressure, electric field, and magnetic proximity effect. The manipulation of topological phases in MTIs provides an exciting avenue for advancing both fundamental research and practical applications. As this field continues to develop, further investigations into the interplay between topology and magnetism in MTIs will undoubtedly pave the way for innovative breakthroughs in the fundamental understanding of topological physics as well as practical applications.

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Section: Scaling Behavior During Quantum Phase Transitions In Finite-...mentioning

confidence: 87%

Section: Scaling Behavior During Quantum Phase Transitions In Finite-...mentioning

confidence: 99%

Manipulating Topological Phases in Magnetic Topological Insulators

Qiu,

Yang,

Chong

et al. 2023

Nanomaterials

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“…In this article, we report a measurement scheme that improves the robustness of the zero-magnetic-field QAHE at higher currents 31 . This is achieved through the simultaneous injection of current into two disconnected perimeters of a multi-terminal Corbino device.…”

Section: Proof Of Conceptmentioning

confidence: 99%

A balanced quantum Hall resistor

Fijalkowski,

Liu,

Klement

et al. 2024

Nat Electron

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The quantum anomalous Hall effect in magnetic topological insulators has potential for use in quantum resistance metrology applications. Electronic conductance is quantized to e2/h (where e is the elementary charge and h is the Planck constant) due to the effect, which persists down to zero external magnetic field and is compatible with the quantum standard of voltage. However, metrological applications of the quantum anomalous Hall effect are currently restricted by the need for low measurement currents and low temperatures. Here we report a measurement scheme that increases the robustness of a zero-magnetic-field quantum anomalous Hall resistor and extends its operating range to higher currents. In the scheme, we simultaneously inject current into two disconnected perimeters of a multi-terminal Corbino device, which is based on V0.1(Bi0.2Sb0.8)1.9Te3, to balance the electrochemical potential between the edges. This screens the electric field that drives backscattering through the bulk and thus improves the stability of the quantization at increased currents. Our approach could also be applied to existing quantum resistance standards that rely on the integer quantum Hall effect.

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Macroscopic Quantum Tunneling of a Topological Ferromagnet

et al. 2023

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The recent advent of topological states of matter spawned many significant discoveries. The quantum anomalous Hall (QAH) effect is a prime example due to its potential for applications in quantum metrology, as well as its influence on fundamental research into the underlying topological and magnetic states and into axion electrodynamics. Here, electronic transport studies on a (V,Bi,Sb) 2 Te 3 ferromagnetic topological insulator nanostructure in the QAH regime are presented. This allows access to the dynamics of an individual ferromagnetic domain. The domain size is estimated to be in the 50-100 nm range. Telegraph noise resulting from the magnetization fluctuations of this domain is observed in the Hall signal. Careful analysis of the influence of temperature and external magnetic field on the domain switching statistics provides evidence for quantum tunneling (QT) of magnetization in a macrospin state. This ferromagnetic macrospin is not only the largest magnetic object in which QT is observed, but also the first observation of the effect in a topological state of matter.

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Macroscopic Quantum Tunneling of a Topological Ferromagnet

Cited by 3 publications

References 44 publications

Manipulating Topological Phases in Magnetic Topological Insulators

Manipulating Topological Phases in Magnetic Topological Insulators

A balanced quantum Hall resistor

Macroscopic Quantum Tunneling of a Topological Ferromagnet

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