AC behaviour and loss phenomena in quantum Hall samples

Schurr, J.; Melcher, J.; Campenhausen, A. Von; Hein, G.; Ahlers, F. J.; Pierz, K.

doi:10.1088/0026-1394/39/1/2

Cited by 22 publications

(36 citation statements)

References 35 publications

(45 reference statements)

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“…This behaviour originates in the exponential increase of the localisation length with increasing Landau band index. Due to the applied frequencyhω/V = 0.008 the σ xy plateau is not flat, but rather has a parabola shape near the minimum at ν = 1.0, similar to what has been observed in experiment [24]. An example of the deviation of σ xy (ω) from its quantised dc value is shown on the right hand side of Fig.…”

Section: Frequency Dependent Hall-conductivitysupporting

confidence: 80%

“…A power-law curve ∼ ω 0.5 can be fitted to the data points. Using this empirical relation, we find a relative deviation of the order of 5 · 10 −6 when extrapolated down to to 1 kHz, the frequency usually applied in metrological experiments [21,22,23,24]. Therefore, there is no quantisation in the neighbourhood of integer filling even in an ideal 2d electron gas without contacts, external leads, and other experimental imperfections.…”

Section: Frequency Dependent Hall-conductivitymentioning

confidence: 87%

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Frequency Dependent Electrical Transport in the Integer Quantum Hall Effect

Schweitzer

2003

Anderson Localization and Its Ramifications

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Section: Frequency Dependent Hall-conductivitysupporting

confidence: 80%

Section: Frequency Dependent Hall-conductivitymentioning

confidence: 87%

Frequency Dependent Electrical Transport in the Integer Quantum Hall Effect

Schweitzer

2003

Anderson Localization and Its Ramifications

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“…3) [24] and comparable to that of GaAs devices not double shielded without a metal backplane. Furthermore, the frequency coefficient of the graphene device is negative whereas all previously reported GaAs devices show a positive frequency coefficient [24,12]. In fact, parasitic capacitances can lead to both positive and negative frequency dependence (while the dissipation factor is always positive).…”

mentioning

confidence: 57%

“…First of all, the graphene plateau is flat within 1 part in 10 7 , or even better, at all measured frequencies over a range of several tesla, exhibiting no frequency-dependent curvature. In contrast, GaAs devices show a strong plateau curvature proportional to frequency [24] which originates from the dissipative part of the capacitances between the 2DES and surrounding metals [25]. In GaAs devices, this effect compromises the precision of the application as an impedance standard unless it is eliminated by the double-shielding method [13].…”

mentioning

confidence: 99%

Towards a graphene-based quantum impedance standard

Kalmbach

Schurr

Ahlers

et al. 2014

Applied Physics Letters

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Precision measurements of the quantum Hall resistance with alternating current (ac) in the kHz range were performed on epitaxial graphene in order to assess its suitability as a quantum standard of impedance. The quantum Hall plateaus measured with alternating current were found to be flat within one part in 10 7 . This is much better than for plain GaAs quantum Hall devices and shows that the magnetic-fluxdependent capacitive ac losses of the graphene device are less critical. The observed frequency dependence of about -8×10 -8 /kHz is comparable in absolute value to the positive frequency dependence of plain GaAs devices, but the negative sign is attributed to stray capacitances which we believe can be minimized by a careful design of the graphene device. Further improvements thus may lead to a simpler and more user-friendly quantum standard for both resistance and impedance.Graphene is probably the most fascinating electronic material discovered in the last decades [1][2][3]. Among its various unique properties, an anomalous 'half-integer' quantum Hall effect (QHE) is most interesting for metrology, where the fact that the Hall resistance is quantized and depends only on fundamental constants is utilized for the representation and maintenance of the resistance unit, the ohm. Typically, twodimensional electron systems (2DES) realized in GaAs/AlGaAs heterostructures [4] are used for this purpose. The required relative measurement uncertainty of better than 1 part in 10 8 is, however, only obtained at strong magnetic fields around 10 tesla and at temperatures of 1.4 kelvin and below. In contrast, in graphene the cyclotron energy splitting between the Landau levels (which is the main factor determining the robustness of the quantized Hall resistance (QHR)) is so large that fingerprints of the QHE are even observed at room temperature [5]. Thus, with graphene a highly precise QHR standard working at low magnetic fields and temperatures above 4 kelvin is conceivable, which would be an enormous advantage for practical metrology. In fact, when measuring with direct current (dc), it has been demonstrated already that the precision of the QHE in high quality graphene devices matches that of GaAs devices [6][7][8][9]. However, in the forthcoming fundamental constant-based redefinition of the Système International d'Unités (SI) [10], also the impedance units (capacitance and inductance) will be traced to fundamental constants [11]. The most direct way to represent the impedance units is to use a quantum Hall resistance measured with alternating current (ac QHR). This has two advantages. Firstly, deriving the resistance and impedance units from the same quantum effect improves the consistency of the SI. And secondly, using the same QHE device at dc and at ac in one and the same cryomagnetic system would constitute a practical and economical advantage. Therefore, the question naturally arises whether graphene can replace GaAs also in the realm of impedance units, leading to an at least equally precise, but more userfriendl...

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“…The measured 2ω signals of V H are about 2000 times larger than the estimated 2ω component due to a possible nonlinear effect. A capacitive effect, such as those observed in the AC quantum Hall effect [17], could be considered as well. However, the frequency of the AC current used in our measurement is low enough (∼17 Hz) that such effects are not important.…”

mentioning

confidence: 99%

Nonlinear response of ultrathin Ni films in degenerate four-photon spectroscopy

Kuznetsova¹,

Petnikova²,

Руденко³

et al. 2000

Quantum Electron.

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We report on a measurement of giant second-harmonic Hall voltages which occur without a magnetic field and do not change their sign on current reversal in a two-dimensional electron system with a transverse density gradient. A quadratic dependence on the electric field, a strong temperature dependence, and both magnitude and directional dependence on the magnetic field are also observed. Such behavior points towards a plausible explanation based on a novel spin Hall effect with in-plane spin polarization.

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AC behaviour and loss phenomena in quantum Hall samples

Cited by 22 publications

References 35 publications

Frequency Dependent Electrical Transport in the Integer Quantum Hall Effect

Frequency Dependent Electrical Transport in the Integer Quantum Hall Effect

Towards a graphene-based quantum impedance standard

Nonlinear response of ultrathin Ni films in degenerate four-photon spectroscopy

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