<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mi>f</mml:mi></mml:math>noise in electron glasses

Shtengel, Kirill; Yu, Clare C.

doi:10.1103/physrevb.67.165106

Cited by 25 publications

(27 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The effect of such a randomly changing field on localized electrons aside from from the hopping clusters should be qualitatively similar to that of thermal fluctuations that may lead to the 1/f noise, for example following one of the scenarios described in Refs. [22,23,24,25,26]. Recent experiments for hopping in quasi-3D samples [48,49], showing a very slow change of 1/f noise intensity at T → 0, seem qualitatively compatible with this interpretation.…”

Section: Discussionsupporting

confidence: 70%

“…In particular, many studies [18] have found that C (f ) /f ∝ 1/f p , where p is typically between 1 and 2. For the particular case of hopping conduction, two major theories of 1/f noise have been suggested, based, respectively, on "carrier number" fluctuations [22,23,24] and "mobility" fluctuations [25,26] as possible origins of the noise. Unfortunately, both theories have been developed for the case of substantially nonvanishing temperatures, for which an accurate numerical study of noise is difficult even with currently available advanced simulation algorithms and supercomputer resources.…”

Section: Current Fluctuationsmentioning

confidence: 99%

See 1 more Smart Citation

A numerical study of Coulomb interaction effects on 2D hopping transport

Kinkhabwala¹,

Sverdlov²,

Likharev³

2006

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

Abstract. We have extended our supercomputer-enabled Monte Carlo simulations of hopping transport in completely disordered 2D conductors to the case of substantial electron-electron Coulomb interaction. Such interaction may not only suppress the average value of hopping current, but also affect its fluctuations rather substantially. In particular, the spectral density S I (f ) of current fluctuations exhibits, at sufficiently low frequencies, a 1/f -like increase which approximately follows the Hooge scaling, even at vanishing temperature. At higher f , there is a crossover to a broad range of frequencies in which S I (f ) is nearly constant, hence allowing characterization of the current noise by the effective Fano factor F ≡ S I (f ) /2e I . For sufficiently large conductor samples and low temperatures, the Fano factor is suppressed below the Schottky value (F = 1), scaling with the length L of the conductor asThe exponent α is significantly affected by the Coulomb interaction effects, changing from α = 0.76 ± 0.08 when such effects are negligible to virtually unity when they are substantial. The scaling parameter L c , interpreted as the average percolation cluster length along the electric field direction, scales as L c ∝ E −(0.98±0.08) when Coulomb interaction effects are negligible and L c ∝ E −(1.26±0.15) when such effects are substantial, in good agreement with estimates based on the theory of directed percolation.

show abstract

Section: Discussionsupporting

confidence: 70%

Section: Current Fluctuationsmentioning

confidence: 99%

A numerical study of Coulomb interaction effects on 2D hopping transport

Kinkhabwala¹,

Sverdlov²,

Likharev³

2006

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

show abstract

“…Another model involved unpaired and non-interacting electrons randomly hopping between traps with different spin orientations and a 1/f distribution of trap energies [14]. Quite often hopping conductivity models are used for 1/f noise in solid state systems [15][16][17] …”

Section: Clusters Of Interacting Two-level-systems (Tls)likely Due To Fmentioning

confidence: 99%

Ising-Glauber Spin Cluster Model for Temperature-Dependent Magnetization Noise in SQUIDs

2014

Phys. Rev. Lett.

View full text Add to dashboard Cite

Clusters of interacting two-level-systems (TLS),likely due to F+ centers at the metal-insulator interface, are shown to self consistently lead to 1/f α magnetization noise in SQUIDs. By introducing a correlation-function calculation method and without any a priori assumptions on the distribution of fluctuation rates, it is shown why the flux noise is only weakly temperature dependent with α < ∼ 1, while the inductance noise has a huge temperature dependence seen in experiment, even though the mechanism producing both spectra is the same. Though both ferromagnetic-RKKY and short-range-interactions (SRI) lead to strong flux-inductance-noise cross-correlations seen in experiment, the flux noise varies a lot with temperature for SRI. Hence it is unlikely that the TLS's time reversal symmetry is broken by the same mechanism which mediates surface ferromagnetism in nanoparticles and thin films of the same insulator materials. PACS numbers: 85.25.Dq, 03.67.Lx Superconducting quantum interference devices (SQUID) are of considerable interest for quantum information as they can replicate natural qubits, such as electron and nuclear spins, using macroscopic devices. However the performance of superconducting qubits is severely impeded by the presence of 1/f magnetization noise which limits their quantum coherence. This type of noise was first observed in SQUIDs well over two decades ago [1,2], however its origins and many of its features remain unexplained. Recent activity in quantum computing has however revived interests to better understand this magnetization noise. [3,4].Magnetic noise in SQUIDs has several puzzling features. While the flux noise (the first spectrum) is also weakly dependent on temperature, the choice of the superconducting material and the SQUID's area [1,5,6] -the inductance noise (the second spectrum or the noise of the flux noise), surprisingly shows a strong temperature dependence. It decreases with increasing temperature and scales as 1/f α [5] where the temperature dependent (0 < α(T ) < 1) [7]. The flux noise is also known to be only weakly dependent on geometry and the noise scales as l/w, in the limit w/l << 1 (l is the length and w is the width of the superconducting wire) [8]. This along with recent experiments [5] suggests that flux noise arises from unpaired surface spins which reside at the Experimental evidence also suggests that these surface spins are strongly interacting and that there is a net spin polarization [5] as the 1/f inductance noise is highly correlated with the usual 1/f flux noise. This cross-correlation is inversely proportional to the temperature and is about the order of unity roughly below 100mK. Since inductance is even under time inversion and flux is odd, their three-point crosscorrelation function must vanish unless time reversal symmetry is broken, which indicates the appearance of long range magnetic order. As this further implies that the mechanism producing both the flux-and inductance noise is the same, it is not clear on why only the associated spectrum ...

show abstract

“…Existence of such correlated state will lead to NGC in the resistance noise in such systems [5]. We have investigated the development of such NGC in the fluctuation using two tests, namely, the direct method of the PDF and also the more sensitive second spectrum method.…”

mentioning

confidence: 99%

Non-Gaussian resistance noise in the ferromagnetic insulating state of a hole-doped manganite

2012

View full text Add to dashboard Cite

We report the observation of a large 1/f noise in the ferromagnetic insulating state (FMI) of a hole doped manganite single crystal of La0.80Ca0.20MnO3 which manifests hopping conductivity in presence of a Coulomb gap. The temperature dependent noise magnitude shows a deep within the FMI state, there is a sharp freeze out of the noise magnitude with temperature on cooling. As the material enters the FMI state, the noise becomes non-Gaussian as seen through probability density function and second spectra. It is proposed to arise from charge fluctuations in a correlated glassy phase of the polaronic carriers which develop in these systems as reported in recent simulation studies.PACS numbers: 71.30.+h, 71.27.+a, 72.70.+m Electronic transport through localized states in disordered and correlated electronic systems has been a topic of considerable interest [1,2]. In such systems, long range Coulomb interaction can lead to opening-up of a soft gap in the density of states (referred to as Coulomb gap, ∆ CG ) and hopping conduction in presence of such a gap [3]. Another consequence is emergence of "glassy" slow relaxations of charge carriers arising from a large number of low-lying states separated by barriers [4]. Such a glassy state can lead to enhanced low frequency (f ) non-Gaussian resistance noise (typically with power spectrum varying as 1/f ) arising from charge fluctuations [5,6]. These issues in a Coulomb glass have been reviewed recently [2]. The experimental investigations on these questions are few and were carried out only in the doped semiconductors with electron density close to the critical concentration (n C ) for metal-insulator (MI) transition [7,8] or in 2DEG in MOSFET's[9]. Here, we focus on the issue of non-Gaussian low frequency noise in the Coulomb glass state of a very different material, namely the low hole-doped rare-earth manganites which can have a ferromagnetic insulating (FMI) state below a certain temperature (T ). In these systems, the Coulomb glass phase occurs for the localized polaronic carriers (in sharp contrast to doped semiconductors) which arise due to strong electron-phonon coupling arising from JahnTeller distortion around the Mn 3+ ions.The FMI state of hole doped manganites (La 1−x Ca x MnO 3 ) arises when hole concentration x in LaMnO 3 exceeds the critical concentration for * email: sudeshna@bose.res.in † email: arup@bose.res.in, ferromagnetism x ≈ 0.15 yet it is smaller than the concentration needed for the formation of the metallic ground state x ≥ x C = 0.22. Existence of a Coulomb glass behavior in the FMI state has been inferred from certain transport experiments [10,11] and also predicted theoretically recently [12]. The FMI state in manganite is unique [13]. We observe a large low frequency resistance fluctuations (noise) with non-trivial T dependence in the FMI state and the noise becomes non-Gaussian at temperatures below the onset of the insulating state. At low T well below the transition to the insulating state the noise shows a sharp fall on cooling. We pr...

show abstract

1/fnoise in electron glasses

Cited by 25 publications

References 36 publications

A numerical study of Coulomb interaction effects on 2D hopping transport

A numerical study of Coulomb interaction effects on 2D hopping transport

Ising-Glauber Spin Cluster Model for Temperature-Dependent Magnetization Noise in SQUIDs

Non-Gaussian resistance noise in the ferromagnetic insulating state of a hole-doped manganite

Contact Info

Product

Resources

About