Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · cond-mat/0201491

Low-field magnetoresistance in GaAs 2D holes

S. J. Papadakis·E. P. De Poortere·H. C. Manoharan·J. B. Yau·M. Shayegan·S. A. Lyon
View original source ↗Read source document ↗Export metadata ↓

Abstract

We report low-field magnetotransport data in two-dimensional hole systems in GaAs/AlGaAs heterostructures and quantum wells, in a large density range, $2.5 \times 10^{10} \leq p \leq 4.0 \times 10^{11}$ cm$^{-2}$, with primary focus on samples grown on (311)A GaAs substrates. At high densities, $p \gtrsim 1 \times 10^{11}$ cm$^{-2}$, we observe a remarkably strong positive magnetoresistance. It appears in samples with an anisotropic in-plane mobility and predominantly along the low-mobility direction, and is strongly dependent on the perpendicular electric field and the resulting spin-orbit interaction induced spin-subband population difference. A careful examination of the data reveals that the magnetoresistance must result from a combination of factors including the presence of two spin-subbands, a corrugated quantum well interface which leads to the mobility anisotropy, and possibly weak anti-localization. None of these factors can alone account for the observed positive magnetoresistance. We also present the evolution of the data with density: the magnitude of the positive magnetoresistance decreases with decreasing density until, at the lowest density studied ($p = 2.5 \times 10^{10}$ cm$^{-2}$), it vanishes and is replaced by a weak negative magnetoresistance.

Explore related subjects

cond-mat.mes-hall

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

S. J. Papadakis, E. P. De Poortere, H. C. Manoharan, J. B. Yau, M. Shayegan, S. A. Lyon. 2002-01-26. Low-field magnetoresistance in GaAs 2D holes. https://doi.org/10.1103/physrevb.65.245312

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Conductivity of charge-neutral multicomponent 2D electron-hole system

The interplay between distinct carrier species in systems with broken Galilean invariance can give rise to a rich landscape of interaction-driven transport phenomena. Here, we develop a comprehensive theory of the electrical conductivity of a two-dimensional mixture of massless Dirac and massive fermions, a system realized in HgTe quantum wells tuned to the charge-neutrality point. In this regime, all carriers are thermally activated, enabling a self-consistent, temperature-dependent interplay between the two species. Crucially, the charge-neutrality condition ensures that the chemical potential is not externally pinned but is determined self-consistently, thereby making the system's transport response an intrinsic probe of inter-species quantum friction. We demonstrate that the conductivity changes with temperature : at low temperatures, transport is dominated by massless Dirac carriers, yielding a nearly temperature-independent conductivity reminiscent of the charge-neutrality point in pristine graphene. As the temperature rises, massive holes become thermally excited, and their mutual scattering with Dirac carriers induces a specific nonmonotonic temperature dependence of the conductivity in both clean and disordered structures. In particular, in nearly clean structures with strong screening modeled by a short-range interparticle interaction potential, the system's conductivity can exhibit an inverse-quadratic temperature dependence. Conversely, in disordered structures with a long-range interparticle interaction, it varies quadratically with temperature. Our findings establish HgTe quantum wells at charge neutrality as a clean, highly tunable platform for isolating and quantitatively studying interaction-driven transport in the absence of Galilean invariance, offering a direct pathway to explore regimes where interparticle collisions dominate over disorder.

cond-mat.mes-hall↗
arXiv2026

Spin-conserving and spin-flip magnetic scattering in the altermagnetic spin-splitter effect

Critical magnetic fluctuations scatter electrons strongly near an ordering transition, but they barely degrade the charge current, because they scatter mostly through small angles. In an altermagnet the electric field also drives a spin current, and a nearly forward spin flip moves an electron to the other spin band at almost unchanged velocity. We develop a Boltzmann theory of the spin splitter ratio that keeps the full collision operator of quasistatic magnetic fluctuations and its change with the magnetic order. Fluctuations of equal total strength give the same resistivity for every fraction of spin flips, yet they can move the spin splitter ratio in opposite directions. Spin conserving fluctuations relax the spin current at about the charge relaxation rate, whereas forward flips equalize the two spin populations at equal energy at the quasiparticle rate, which in two dimensions grows linearly with the correlation length. Energy conservation on the split bands protects the part of the spin current carried by the band shift of the occupied states at every scattering strength, and the splitting blocks forward flips once the spin Fermi lines lie farther apart than the inverse correlation length. When flips dominate, a quarter to a half of the lattice band ratio survives. The transport time approximation reproduces the initial growth of the resistivity but recovers only a quarter to a half of the initial fall of the ratio, and a disorder series at fixed reduced temperature measures this fall independent of the order amplitude.

cond-mat.mes-hall↗
arXiv2026

Spin conservation protects the altermagnetic spin-splitter current from critical scattering

Near a magnetic transition, critical fluctuations scatter electrons strongly, but the charge current survives, because long wavelength fluctuations barely turn the electron velocity. In an altermagnet the electric field also drives a spin current, the spin splitter effect, and a nearly forward scattering event that flips spin moves an electron to the other spin band at almost unchanged velocity. We show that the spin current shares the protection of the charge current only when the fluctuations conserve spin. Solving the Boltzmann equation with the full collision operator, including its change with the magnetic order, we find that forward flips equalize the two spin populations at equal energy at the quasiparticle rate, which in two dimensions grows linearly with the correlation length, whereas spin conserving fluctuations relax the spin current at a rate comparable to the charge relaxation rate. Fluctuations with the same resistivity can thus move the spin splitter ratio in opposite directions. Energy conservation protects the part of the spin current that follows the band shift of the occupied states, and the splitting blocks forward flips once the spin Fermi lines lie farther apart than the inverse correlation length. A disorder series at fixed reduced temperature measures the initial fall of the ratio with the magnetic resistivity independent of the order amplitude, and the growth of this slope toward the transition identifies spin flip critical fluctuations.

cond-mat.mes-hall↗