Thermal correction to resistivity in dilute 2D Si-based systems

Abstract

We calculate the resistivity of 2D electron (hole) gas, taking into account the degeneracy and the thermal correction due to the combined Peltier and Seebeck effects. The resistivity is found to be universal function of temperature, expressed in units of h e 2 (kF l) −1 . The giant parallel magnetiresistivity found to result from the spin and, if exists, valley splitting of the energy spectrum. Our analysis of compressibility and thermopower points to thermodynamic nature of metal-insulator transition in 2D systems. PACS numbers: 73.40.Qv, 71.30+h, 73.20.Fz Recently, a great deal of interest has been focussed on the anomalous transport behavior of a wide variety of low-density 2D electron [1,2] and hole [3,4,5] systems. It has been found that, below some critical density, the cooling causes an increase in resistivity, whereas in the opposite high density case the resistivity decreases. Another unusual property of dilute 2D systems is their enormous response to parallel magnetic field. At low temperatures the magnetic field found to suppress the metallic behavior of 2D electron(hole) gas and result in strong increasing of resistivity upon enhancement of spin polarization degree [6,7]. At high temperatures the parallel magnetoresistivity starts to be unaffected by magnetic field when the temperature exceeds a value being of the order of Zeeman energy. A strong perpendicular magnetic field, if applied simultaneously with the parallel one, results in suppression of parallel magnetoresistivity [8]. Although numerous theories have been put forward to account for these effects, the origin of the above behavior is still the subject of a heated debate.The ohmic measurements known to be carried out at low current I → 0 in order to prevent heating. Usually, only the Joule heat is considered to be important. In contrast to the Joule heat, the Peltier and Thomson effects are linear in current. As shown in Refs. [9,10,11], the Peltier effect influences ohmic measurements and results in a correction to a measured resistance. When current is flowing, one of the sample contacts is heated, and the other cooled, because of the Peltier effect. The contact temperatures are different. The voltage drop across the circuit includes the Seebeck thermoelectromotive force, which is linear in current. Finally, there exists a thermal correction ∆ρ, to the ohmic resistivity, ρ, of the sample. For degenerate electrons, ∆ρ/ρ ∼ (kT /µ) 2 , where µ is the Fermi energy. Hence, the correction may be comparable with the ohmic resistance of a sample when kT ∼ µ.In the present paper, we report on a study of low-T transport in 2D electron(hole) gas, taking into account both the electron degeneracy and the Peltier-effectinduced correction to resistivity. [9,10]. The parallel magnetoresistivity found to originate from the spin and,if exists, valley splitting of 2D energy spectrum.Let us consider, for clarity, the (100) MOSFET 2DEG system. The electrons are assumed to occupy the first quantum-well subband with isotropic energy spectrum ε(k) =h 2 k 2 2m...

The success of Fermi gas model for overall scaling of 2D metal-to-insulator transition data

“…[15] low-T transport in dilute 2D systems has been analyzed taking into account both the carrier degeneracy and so-called thermal correction [16] owing to Peltier and Seebeck thermoelectric effects combined. For standard ohmic measurements setup, the small applied current causes heating(cooling) at the first(second) sample contact due to the Peltier effect.…”

Surprising coincidence of the apparent 2D metal-to-insulator transition data with Fermi-gas based model results

“…In Ref. [15] low-T transport in dilute 2D systems has been analyzed taking into account both the carrier degeneracy and so-called thermal correction [16] owing to Peltier and Seebeck thermoelectric effects combined. For standard ohmic measurements setup, the small applied current causes heating(cooling) at the first(second) sample contact due to the Peltier effect.…”

Классическое Магнетосопротивление Двухкомпонентной Системы, Обусловленное Термоэлектрическими Эффектами

“…В работах [26][27][28][29] было показано, что при протека-нии постоянного тока через образец с металлическими контактами термоэлектрический эффект приводит к воз-никновению возмущения температуры носителей, кото-рое может быть неоднородным по образцу и вызывает поправку к наблюдаемой величине тока. В работах [34] изучался электрический и тепловой транспорт в одно-слойном графене в рамках гидродинамической модели, то есть в условиях, когда самыми быстрыми являются межчастичные столкновения.…”