Interaction effects in conductivity of a two-valley electron system in high-mobility Si inversion layers

Klimov, Nikolai N.; Knyazev, D. A.; Omel’yanovskii, O. E.; Pudalov, V. M.; Kojima, H.; Gershenson, M. E.

doi:10.1103/physrevb.78.195308

Cited by 37 publications

(69 citation statements)

References 72 publications

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“…This qualitative model is roughly similar to the charged trap model by Alltshuler and Maslov [93], but relates the traps with the spin droplets inside the 2D layer, rather than with defects at the Si-SiO 2 interface. In principle, the presence of the spin droplets is expected to cause saturation of the temperature dependence of the phase breaking time [94], however, we did not reveal the τ ϕ saturation down to about 30 mK [58]; possible explanation of the low saturation temperature is discussed in Ref. [94].…”

Section: Possible Origin Of the Two Channel Scatteringmentioning

confidence: 65%

“…[67]). For high-mobility samples, the upturn sets upon lowering temperature, (T < 1/τ ; T < τ v ), where the effective number of triplet terms diminishes [58], and/or at higher densities where F σ 0 diminishes [20,24,59,69,70]; these low-temperature and high-density regimes are out of sight in Fig. 2.…”

Section: High-and Low-mobility Samplesmentioning

confidence: 99%

“…The latter, δσ(T ) = γ(B 2 /T ) + ηT , was calculated using experimentally determined F σ 0 (n) values [20,58], and σ D found from a standard procedure [59]. In order to cut off the corrections above a certain border temperature [92] and, thus, to disentangle the exponential-and linear-in-T contributions, the calculated interaction correction are cut-off with an exponential crossover function above T B , which for simplicity, we set equal to ∆(n)/2.…”

Section: Phenomenological Model For Transport and Magnetotransportmentioning

confidence: 99%

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Novel energy scale in the interacting two-dimensional electron system evidenced from transport and thermodynamic measurements

2016

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We study how the non-Fermi-liquid two-phase state reveals itself in transport properties of highmobility Si-MOSFETs. We have found features in zero-field transport, magnetotransport, and thermodynamic spin magnetization in a 2D correlated electron system that may be directly related with the two-phase state. The features manifest above a density dependent temperature T * that represents a novel high-energy scale, apart from the Fermi energy. More specifically, in magnetoconductivity, we found a sharp onset of the novel regime δσ(B, T ) ∝ (B/T ) 2 above a density-dependent temperature T kink (n), a high-energy behavior that "mimics" the low-temperature diffusive interaction regime. The zero-field resistivity temperature dependence exhibits an inflection point T infl (n). In thermodynamic magnetization, the weak-field spin susceptibility per electron, ∂χ/∂n changes sign at T dM/dn (n). All three notable temperatures, T kink , T infl , and T dM/dn , behave critically ∝ (n − nc), are close to each other, and are intrinsic to high-mobility samples solely; we therefore associate them with an energy scale T * caused by interactions in the 2DE system. [5][6][7], metal-insulator transition (MIT) [1,5,[8][9][10], strong positive magnetoresistance (MR) in parallel field [11][12][13][14][15][16][17][18], strong renormalization of the effective mass and spin susceptibility [2,[19][20][21][22][23][24], etc.Far away from the critical MIT density n c , in the well "metallic regime," these effects are explained within the framework of the Fermi liquid theory -either in terms of interaction quantum corrections (IC) [25,26], or temperaturedependent screening of the disorder potential [27][28][29][30][31]. Both theoretical approaches so far are used to treat the experimental data on transport, and the former one -also to determine the Fermi liquid coupling constants from fitting the transport and magnetotransport data to the IC theory. In the close vicinity of the critical region, conduction is treated within the renormalization group [32][33][34][35][36], or the Wigner-Mott approach [37,38].On the other side, a number of theories predicts breakdown of the uniform paramagnetic 2D Fermi liquid state due to instability in the spin or charge channel, developing as interaction strength increases [39][40][41][42][43]. However, how the potential instabilities reveal themselves in charge transport remains an almost unexplored question.On the spin polarization of the 2D electron system Spin fluctuations are believed to play an important role in the 2DE system, especially near the apparent metalinsulator transition. Ferromagnetic instabilities result from the interplay of the electronic interactions and the Pauli principle. The interaction energy can be minimized when the fermion antisymmetry requirement is satisfied by the spatial wave function resulting in the alignment of spins and a large ground-state spin magnetization. In clean metals, the long-range part of the Coulomb interaction is screened, whereas its short-range part leads to s...

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Section: Possible Origin Of the Two Channel Scatteringmentioning

confidence: 65%

Section: High-and Low-mobility Samplesmentioning

confidence: 99%

Section: Phenomenological Model For Transport and Magnetotransportmentioning

confidence: 99%

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Novel energy scale in the interacting two-dimensional electron system evidenced from transport and thermodynamic measurements

2016

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Section: Pacs Numbersmentioning

confidence: 99%

“…These measurements were carried out by different experimental groups and, furthermore, were performed on silicon field-effect structures made by different manufacturers. According to 4,10 , the experimental data obtained for the effective mass can be well described by the interpolation formula m = 0.205m e (1 + 0.035r s + 0.00016rin the range 8 > r s > 1.5, where r s = 2.63(10/n s ) 1/2 and the electron density is measured in units of 10 11 cm −2 . Figure 1 shows the dependence of the effective mass on the electron density as a plot of m b n s /m versus n s , where m b = 0.19m e is the band effective mass.…”

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Two-dimensional electrons in (100)-oriented silicon field-effect structures in the region of low concentrations and high mobilities

Dolgopolov

2015

Jetp Lett.

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A comparative analysis of experimental data on electron transport in Si (100) MOSFETs in the region of high mobilities and strong electron-electron interaction is carried out. It is shown that electrons can be described by the model of a noninteracting gas with the renormalized mass and Lande factor, which allows experimentally verifiable predictions. PACS numbers:Although the experimental studies of the two-dimensional electron gas in silicon field-effect structures already have a history of more than half a century 1 , they still go on (see, e.g., 2-4 ). Interest in this field of research is mainly related to the possible metal-insulator transition 5 , as well as the manifestations of strong electron-electron interaction 2-4,9-11 for the lowest attainable electron densities on the order of 10 11 cm −2 . In this range of electron densities, the effect of electronelectron interaction cannot be described in terms of a perturbation theory series, because the expansion parameter r s is considerably larger than unity. Therefore, experimental results should be interpreted very cautiously and, in the first place, one needs to identify the common features revealed in experiments on samples from different manufacturers by different research groups using different methods of experimental data treatment. In this publication, a part of this program is performed and some further experiments are suggested.Almost noninteracting quasiparticles carrying a unit charge exist only very close to the Fermi energy. For them, one can define the Fermi momentum p F , determined by the number of free electrons introduced into the originally neutral system; the velocity v F ; and the Lande factor g * , which characterizes only the quasiparticles at the Fermi surface. Each of these quantities can be measured experimentally.The most convenient and accurate experimental method to find the relation between the Fermi momentum and Fermi velocity is to determine the electron effective mass m = p F /v F from the analysis of the temperature dependence of the amplitude and shape of the Shubnikov-de Haas oscillations. It is appropriate to begin the analysis of experimental results with measurements of this kind. However, it is necessary to take into account a number of factors that compel one to treat with some caution even these most reliable data. (i) The amplitude of quantum oscillations needs to be sufficiently small both because of the limitation on the validity of the Lifshitz-Kosevich formula and because of the possible strong nonparabolicity of the spectrum 12 in the vicinity of the Fermi level. The effective mass is overestimated owing to the first factor and underestimated owing to the second. (ii) The quantum oscillation numbers have to be sufficiently large to satisfy the assumptions made in the Lifshitz-Kosevich theory. (iii) The quantum relaxation time has to be independent of the temperature. Otherwise, the effective mass will be overestimated or underestimated, depending on the temperature range 4 .Raw experimental data on the measur...

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Non‐Fermi‐Liquid Behavior of Superconducting SnH₄

Troyan,

Semenok,

Ivanova

et al. 2023

Advanced Science

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The chemical interaction of Sn with H2 by X‐ray diffraction methods at pressures of 180–210 GPa is studied. A previously unknown tetrahydride SnH4 with a cubic structure (fcc) exhibiting superconducting properties below TC = 72 K is obtained; the formation of a high molecular C2/m‐SnH14 superhydride and several lower hydrides, fcc SnH2, and C2‐Sn12H18, is also detected. The temperature dependence of critical current density JC(T) in SnH4 yields the superconducting gap 2Δ(0) = 21.6 meV at 180 GPa. SnH4 has unusual behavior in strong magnetic fields: B,T‐linear dependences of magnetoresistance and the upper critical magnetic field BC2(T) ∝ (TC – T). The latter contradicts the Wertheimer–Helfand–Hohenberg model developed for conventional superconductors. Along with this, the temperature dependence of electrical resistance of fcc SnH4 in non‐superconducting state exhibits a deviation from what is expected for phonon‐mediated scattering described by the Bloch‐Grüneisen model and is beyond the framework of the Fermi liquid theory. Such anomalies occur for many superhydrides, making them much closer to cuprates than previously believed.

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Interaction effects in conductivity of a two-valley electron system in high-mobility Si inversion layers

Abstract: We have measured the conductivity of high-mobility (001) Si metal-oxide-semiconductor field effect transistors (MOSFETs) over wide ranges of electron densities n = (1.

Cited by 37 publications

References 72 publications

Novel energy scale in the interacting two-dimensional electron system evidenced from transport and thermodynamic measurements

Novel energy scale in the interacting two-dimensional electron system evidenced from transport and thermodynamic measurements

Two-dimensional electrons in (100)-oriented silicon field-effect structures in the region of low concentrations and high mobilities

Non‐Fermi‐Liquid Behavior of Superconducting SnH₄

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Interaction effects in conductivity of a two-valley electron system in high-mobility Si inversion layers

Abstract: We have measured the conductivity of high-mobility (001) Si metal-oxide-semiconductor field effect transistors (MOSFETs) over wide ranges of electron densities n = (1.

Cited by 37 publications

References 72 publications

Novel energy scale in the interacting two-dimensional electron system evidenced from transport and thermodynamic measurements

Novel energy scale in the interacting two-dimensional electron system evidenced from transport and thermodynamic measurements

Two-dimensional electrons in (100)-oriented silicon field-effect structures in the region of low concentrations and high mobilities

Non‐Fermi‐Liquid Behavior of Superconducting SnH4

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Product

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Non‐Fermi‐Liquid Behavior of Superconducting SnH₄