Giant<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 perovskite manganites: Evidence of the percolation threshold

Podzorov, Vitaly; Uehara, M.; Gershenson, M. E.; Koo, Tae‐Yeong; Cheong, Sang‐Wook

doi:10.1103/physrevb.61.r3784

Cited by 111 publications

(90 citation statements)

References 21 publications

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“…They were detected with SQUID also in antiferromagnetic thin films [15] and on superparamagnetic nanoparticles [16]. Other ways to detect 1/f magnetic noise is by following the resistance fluctuations close to a certain ferromagnetic transition (colosal magnetoresistance) [17], and to observe the electrical noise generated in small Hall probe contacts [18]. The 1/f noise generated in the Hall contacts is much larger than the usual 1/f noise measured in the same system which is unrelated to magnetic fluctuations.…”

Section: −1mentioning

confidence: 99%

1/f Spin noise and a single spin detection with STM

Manassen

Balatsky

2004

Israel Journal of Chemistry

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We propose a novel mechanism for single spin detection based on the 1/f spin current noise. We postulate the 1/f spin noise for the tunneling current, similar to the ubiquitous 1/f noise in magnetic systems. Magnetic coupling between tunneling electrons and localized spin S then leads to the peak at Larmor frequency in the power spectrum of the electric current fluctuations I 2 ω . The elevated noise in the current spectrum will be spatially localized near the magnetic site. The difference in the power spectra taken at the Larmor frequency and elsewhere would reveal the peak in the spectrum. We argue that signal to noise ratio for this mechanism is on the order one.In addition we discuss the asymmetric lineshapes observed regularly with this measurement. We show that such lineshapes are in accordance to the random sampling done with the tunneling electrons. Yet, this predicts a linewidth at least one order of magnitude larger than observed experimentally which is likely to be due to electrostatic repulsion between the tunneling electrons and temporal correlations in the tunneling process. 1/F SPIN NOISEThe phenomenon of 1/f (flicker) noise is known for almost 80 years [1]. It describes the deviation from the flat spectral density expected from a current made of uncorrelated charge carriers -at low frequencies. In this range, the spectral density was found to obey a power law of the form 1/f α where f is the frequency, and α = 0.5 − 1.5. Flicker noise appears in endless number of electronic devices, in music [2] in ocean streams [3,4] and in many entirely different systems. This is one of the most universal phenomena, yet, one of the largest enigmas in physical sciences.An early explanation to this phenomenon was that the 1/f noise can arise from a superposition of relaxation processes [5]. In this model the noise is described as a superposition of consecutive random events, each starts at a certain time t 0 and follow a simple exponential relaxation law: N (t − t 0 ) = N 0 e −(t−t0)/τ . The power spectrum of one such event is a Lorentzian. The power spectrum of a large number of such consecutive random events, all with the same τ is also a Lorentzian. If, on the other hand, there is a distribution of relaxation times P (τ ) ∼ 1/τ , from τ 1 to τ 2 than the overall spectral density will obey a power law ∼ 1/f in the range between τ −1 1 and τ −1 2 . A common denominator to many mechanisms proposed for different 1/f phenomena [6,7] is a distribution of relaxation times.1/f noise is ubiquitous in STM tunneling current although its origins are a source of continuous mystery that is not fully understood until now [8,9,10,11]. Unlike the well known shot noise 1/f noise is proportional to the square of the current such that: I 2 (ω) /I 2 = const. Where I 2 (ω) is the spectral density of current fluctuations (in units of A 2 /Hz) and I is the current. Empirically, the current fluctuations in 1/f noise are known to obey the Hooge formulawhere N are the number of current carriers in the sample and a is of the order of 0....

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Section: −1mentioning

confidence: 99%

1/f Spin noise and a single spin detection with STM

Manassen

Balatsky

2004

Israel Journal of Chemistry

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“…Also resistivity noise measurements reveal two-level fluctuations 8 related to the phase separation scenario 9 , including mixed-phase states of different magnetic and electrical properties. In this context, the observed magnetic field induced metal-insulator transition 10 reflects the percolative growth of conducting FM clusters embedded in an AFM matrix 11 . In the present article, we investigate the stability of the low temperature AFM phase of a Nd 0.5 Ca 0.5 MnO 3 single crystal using ac and dc magnetization measurements.…”

Section: Introductionmentioning

confidence: 99%

Cooling-rate dependence of the antiferromagnetic domain structure of a single-crystal charge-ordered manganite

et al. 2002

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The low temperature phase of single crystals of Nd0.5Ca0.5MnO3 and Gd0.5Ca0.5MnO3 manganites is investigated by squid magnetometry. Nd0.5Ca0.5MnO3 undergoes a charge-ordering transition at TCO=245K, and a long range CE-type antiferromagnetic state is established at TN =145K. The dc-magnetization shows a cooling rate dependence below TN , associated with a weak spontaneous moment. The associated excess magnetization is related to uncompensated spins in the CE-type antiferromagnetic structure, and to the presence in this state of fully orbital ordered regions separated by orbital domain walls. The observed cooling rate dependence is interpreted to be a consequence of the rearrangement of the orbital domain state induced by the large structural changes occurring upon cooling.

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“…[4][5][6][7][8] . The noise peak around M-I transition has been interpreted in terms of percolative nature of the transition between charge ordered insulating and metallic ferromagnetic states, 6 or in terms of magnetic fluctuations coupled to the resistivity. 7 It became however soon evident that this unusually large 1/f noise is not an intrinsic property of doped manganites.…”

Section: Introductionmentioning

confidence: 99%

“…4 Early experiments concentrated on the noise peak associated with M-I transition, in the vicinity of which a 3 to 4 order of magnitude increase of the noise level has been observed in Ca and Sr doped manganites, see e.g. [4][5][6][7][8] . The noise peak around M-I transition has been interpreted in terms of percolative nature of the transition between charge ordered insulating and metallic ferromagnetic states, 6 or in terms of magnetic fluctuations coupled to the resistivity.…”

Section: Introductionmentioning

confidence: 99%

Bias dependent 1/f conductivity fluctuations in low-doped La1−xCaxMnO3 manganite single crystals

Belogolovskii

Jung

Markovich

et al. 2011

Journal of Applied Physics

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Low frequency noise in current biased La 0.82 Ca 0.18 MnO 3 single crystals has been investigated in a wide temperature range from 79 K to 290 K. Despite pronounced changes in magnetic properties and dissipation mechanisms of the sample with changing temperature, the noise spectra were found to be always of the 1/f type and their intensity (except the lowest temperature studied) scaled as a square of the bias. At liquid nitrogen temperatures and under bias exceeding some threshold value, the behavior of the noise deviates from the quasi-equilibrium modulation noise and starts to depend in a non monotonic way on bias. It has been verified that the observed noise obeys Dutta and Horn model of 1/f noise in solids. The appearance of nonequilibrium 1/f noise and its dependence on bias have been associated with changes in the distribution of activation energies in the underlying energy landscape. These changes have been correlated with bias induced changes in the intrinsic tunneling mechanism dominating dissipation in La 0.82 Ca 0.18 MnO 3 at low temperatures.

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Giant1/fnoise in perovskite manganites: Evidence of the percolation threshold

Cited by 111 publications

References 21 publications

1/f Spin noise and a single spin detection with STM

1/f Spin noise and a single spin detection with STM

Cooling-rate dependence of the antiferromagnetic domain structure of a single-crystal charge-ordered manganite

Bias dependent 1/f conductivity fluctuations in low-doped La1−xCaxMnO3 manganite single crystals

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