Fermi-Liquid Behavior of the Low-Density 2D Hole Gas in a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>GaAs</mml:mi><mml:mi>/</mml:mi><mml:mi>AlGaAs</mml:mi></mml:math>Heterostructure at Large Values of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>r</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>

Proskuryakov, Y. Y.; Savchenko, A. K.; Сафонов, С. С.; Pepper, M.; Simmons, M. Y.; Ritchie, D. A.

doi:10.1103/physrevlett.86.4895

Cited by 36 publications

(33 citation statements)

References 30 publications

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“…The concentration n c corresponding to a change in the sign of the derivative dR/dT , varied widely from sam- ple to sample, depending on the disorder in the electron system under investigation. A similar change in the sign of the derivative dR/dT , corresponding to the critical carrier concentration n c (p c ), was subsequently found in AlGaAs/GaAs heterostructures with two-dimensional electron 71,72 and hole 73,74,75,76,77,78,79,80 gas, quantum wells AlAs with two-dimensional electron gas 81 , as well as quantum SiGe wells with electron 82 and hole 83,84 gas. However, the temperature dependence of the resistance of these low-dimensional systems in the temperature range T < 1K turned out to be much less than that in silicon MOS structures (Fig.…”

Section: Metal-insulator Transition In Two-dimensional Systemsmentioning

confidence: 76%

Quantum phase transitions in two-dimensional systems

Shangina

Dolgopolov

2003

Phys.-Usp.

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Section: Metal-insulator Transition In Two-dimensional Systemsmentioning

confidence: 76%

Quantum phase transitions in two-dimensional systems

Shangina

Dolgopolov

2003

Phys.-Usp.

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Section: Experimental Situationmentioning

confidence: 99%

“…[17]. In measurements of the weak localization [60] and quantum oscillations in a weak perpendicular field [2], a Fermi-liquid type behavior was found with no signatures of the spin polarization of itinerant electrons.Eventually, the thermodynamic spin magnetization measurements performed in a weak field [61] have clarified the reason of the contradiction: the 2D interacting electron system experiences a transition from Fermi liquid to the two-phase state, that hampered interpretation of the data. The main result of the thermodynamic weak field studies is the observation of "spin-droplets" -spin-polarized collective electron states with a total spin of the order of two [61].…”

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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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“…(The existence of the percolative MIT in 2D GaAs structures was proposed earlier in [11].) In this work we use combined compressibility and conductance measurements to shed light on the origin of the apparent MIT in 2D hole gases with large interactions between the carriers -a problem widely debated over the last few years [16,17,18]. We compare the behaviour of the compressibility of holes with that of electrons (with much weaker interactions) and conclude that the apparent MIT in 2D hole gases is not related to a quantum phase transition.…”

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Thermodynamic Density of States of Two-Dimensional GaAs Systems near the Apparent Metal-Insulator Transition

et al. 2006

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We perform combined resistivity and compressibility studies of two-dimensional hole and electron systems which show the apparent metal-insulator transition -a crossover in the sign of ∂R/∂T with changing density. No thermodynamic anomalies have been detected in the crossover region. Instead, despite a ten-fold difference in rs, the compressibility of both electrons and holes is well described by the theory of nonlinear screening of the random potential. We show that the resistivity exhibits a scaling behavior near the percolation threshold found from analysis of the compressibility. Notably, the percolation transition occurs at a much lower density than the crossover. The apparent metal-insulator transition (MIT) in high-mobility two-dimensional systems remains a topic of fundamental interest [1] and continuing debate [2]. The anomaly of these systems is exemplified by the existence of a narrow range of carrier densities around n = n c where the slope of the temperature dependence of the resistance, ∂R/∂T , changes its sign. To unravel a complex interplay between interactions and disorder in this phenomenon, it is essential to combine transport measurements with other experimental probes, in particular measurements of the thermodynamic density of states (also referred to as the charge compressibility [3, 4]) χ = dn/dµ, where µ is the chemical potential. There have been only few measurements of χ near the apparent MIT [5,6,7], among which work [5] on a 2D hole gas with large values of the Coulomb interaction parameter r s ≡ 1/ πna 2 B ≈ 5 − 16 has attracted much attention. (Here a B = 18Å is the effective Bohr radius for the hole mass of 0.38 m 0 .) In their experiments done at T = 0.3 − 1.3 K the authors of Ref. [5] found that the inverse compressibility χ −1 (n) has a minimum which is positioned exactly at n c . This was interpreted as a thermodynamic signature of an interaction-driven phase transition discussed in theoretical works [8,9].An alternative explanation of the minimum of χ −1 (n) can be based on the nonlinear screening theory (NST) [10,11,12,13] that emphasizes the role of disorder. The basic premise of the NST is that a low-density metal is unable to screen fluctuations of potential, so that depletion regions with vanishingly small local density appear and grow as n decreases. The NST predicts that χ −1 (n) has a minimum at n = n m (determined by disorder), and a rapid upturn to positive values at n < n m .This theory also predicts a percolation threshold at n = n p [11], where n p ≈ n m /3 in typical GaAs systems [13]. There have been suggestions, based on the conductance scaling, that the percolation transition is closely related to the change in the sign of ∂R/∂T [12,14,15]. (The existence of the percolative MIT in 2D GaAs structures was proposed earlier in [11].) In this work we use combined compressibility and conductance measurements to shed light on the origin of the apparent MIT in 2D hole gases with large interactions between the carriers -a problem widely debated over the last few years...

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Fermi-Liquid Behavior of the Low-Density 2D Hole Gas in aGaAs/AlGaAsHeterostructure at Large Values ofrs

Cited by 36 publications

References 30 publications

Quantum phase transitions in two-dimensional systems

Quantum phase transitions in two-dimensional systems

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

Thermodynamic Density of States of Two-Dimensional GaAs Systems near the Apparent Metal-Insulator Transition

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