Probing nanocrystalline grain dynamics in nanodevices

Lien

et al. 2020

Nat Commun

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Strong electron correlations have long been recognized as driving the emergence of novel phases of matter. A well recognized example is high-temperature superconductivity which cannot be understood in terms of the standard weak-coupling theory. The exotic properties that accompany the formation of the two-channel Kondo (2CK) effect, including the emergence of an unconventional metallic state in the low-energy limit, also originate from strong electron interactions. Despite its paradigmatic role for the formation of non-standard metal behavior, the stringent conditions required for its emergence have made the observation of the nonmagnetic, orbital 2CK effect in real quantum materials difficult, if not impossible. We report the observation of orbital one- and two-channel Kondo physics in the symmetry-enforced Dirac nodal line (DNL) metals IrO2 and RuO2 nanowires and show that the symmetries that enforce the existence of DNLs also promote the formation of nonmagnetic Kondo correlations. Rutile oxide nanostructures thus form a versatile quantum matter platform to engineer and explore intrinsic, interacting topological states of matter.

Section: Discussionmentioning

confidence: 99%

Oxygen vacancy-driven orbital multichannel Kondo effect in Dirac nodal line metals IrO2 and RuO2

Lien

et al. 2020

Nat Commun

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“…for the ac bridge measurement configuration depicted in Fig. 2 Empirically, to obtain an accurate γ value for a given sample, we write through the free-electron model [27]. Note that extracting γ value by this method excludes any possible contribution from the background noise 0 V S .…”

Section: B Excess Low-frequency Noisementioning

confidence: 99%

“…manifests vibrant TLS phenomena especially in small polycrystalline samples[26,27], where m is the effective electron mass, is the averaged electron scattering cross section, with F k being the Fermi wavenumber. ( ) g E can thus be explicitly expressed in terms of the known electronic parameters and the measured ( ) metal, i.e.,…”

mentioning

confidence: 99%

Activation Energy Distribution of Dynamical Structural Defects in RuO2 Films

Gao

et al. 2018

Phys. Rev. Applied

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Ruthenium dioxide (RuO2) is an important metal widely used in nanoelectronic devices. It plays indispensable roles in the applications as catalyst and supercapacitors.A good understanding of the origin of the flicker or 1 f noise in RuO2 will advance the design and efficiency of these applications. We demonstrate in a series of sputtered RuO2 polycrystalline films that the 1 f noise originates from fluctuating oxygen vacancies which act as dynamical structural defects, i.e., moving scattering centers. Reducing the number of oxygen vacancies by adjusting thermal annealing conditions significantly reduces the noise magnitude γ , the Hooge parameter. We quantify the activation energy distribution function, ( ) g E , and calculate the oxygen vacancy density, TLS n , from the measured γ value. We show that ( ) g E can be explicitly expressed in terms of ( ) T γ and the electronic parameters of the metal,where T denotes temperature. The inferred TLS n value is in line with the oxygen content determined from the x-ray photoelectron spectroscopy studies.Corresponding authors, *

“…The lock-in technique essentially modulates the low frequency signal due to the DM-CM switching to centre at the carrier frequency, which is high enough to pass through the circuit, and then demodulates to recover the original transition dynamics. Also, modulation to higher frequencies allows the minimisation of the input noise of the current preamplifier [30].…”

Section: Response To a Sinusoidal Voltagementioning

confidence: 99%

Bistable transport properties of a quasi-one-dimensional Wigner solid on liquid helium under continuous driving

Rees

Lee³

et al. 2017

Phys. Rev. B

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We investigate low-frequency fluctuations in the transport characteristics of a quasi-1D Wigner solid (WS) moving along a liquid helium substrate in response to a sinusoidal driving voltage. The fluctuations occur between distinct transport modes in which the decoupling of the WS from ripplonic polarons (or 'dimple lattice', DL) formed on the helium surface does, or does not, occur during each ac cycle. We demonstrate that a Gaussian-like distribution in the decoupling threshold force gives rise to this bistability, as the low-frequency switching occurs when the probability of decoupling during each ac cycle is small but finite. We attribute the distribution in the decoupling threshold force to the range of structural configurations allowed for the quasi-1D electron lattice, which influences the strength of the WS-DL coupling. Hence, the switching rate between the ac transport modes is extremely sensitive to the microscopic properties of the electron solid.