TL;DR: The results indicate that both anticrossings and magnetic phase transitions are also possible in quasi-1D quantum wires in an in-plane B field, Bparallel, and imply that the well-known 0.7 structure may evolve into a spin-hybridized state in finite dc bias.

Abstract: In quantum Hall systems, both anticrossings and magnetic phase transitions can occur when opposite-spin Landau levels coincide. Our results indicate that both processes are also possible in quasi-1D quantum wires in an in-plane $B$ field, ${B}_{\ensuremath{\parallel}}$. Crossings of opposite-spin 1D subbands resemble magnetic phase transitions at zero dc source-drain bias, but display anticrossings at high dc bias. Our data also imply that the well-known 0.7 structure may evolve into a spin-hybridized state in finite dc bias.

In quantum Hall systems, both anticrossings and magnetic phase transitions can occur when oppositespin Landau levels coincide.

The authors results indicate that both processes are also possible in quasi-1D quantum wires in an in-plane B field, Bk. Crossings of opposite-spin 1D subbands resemble magnetic phase transitions at zero dc source-drain bias, but display anticrossings at high dc bias.

The authors data also imply that the well-known 0.7 structure may evolve into a spin-hybridized state in finite dc bias.

Abstract: The integer quantised conductance of one-dimensional electron systems is a well-understood effect of quantum confinement. A number of fractionally quantised plateaus are also commonly observed. They are attributed to many-body effects, but their precise origin is still a matter of debate, having attracted considerable interest over the past 15 years. This review reports on experimental studies of fractionally quantised plateaus in semiconductor quantum point contacts and quantum wires, focusing on the 0.7 × 2e(2)/h conductance anomaly, its analogues at higher conductances and the zero-bias peak observed in the dc source-drain bias for conductances less than 2e(2)/h.

TL;DR: This review reports on experimental studies of fractionally quantised plateaus in semiconductor quantum point contacts and quantum wires, focusing on the 0.7 × 2e(2)/h conductance anomaly, its analogues at higher conductances and the zero-bias peak observed in the dc source-drain bias for conductances less than 1e( 2)/h.

Abstract: The integer quantized conductance of one-dimensional electron systems is a well understood effect of quantum confinement. A number of fractionally quantized plateaus are also commonly observed. They are attributed to many-body effects, but their precise origin is still a matter of debate, having attracted considerable interest over the past 15 years. This review reports on experimental studies of fractionally quantized plateaus in semiconductor quantum point contacts and quantum wires, focusing on the 0.7 x 2e^2/h conductance anomaly, its analogs at higher conductances, and the zero bias peak observed in the d.c. source-drain bias for conductances less than 2e^2/h.

Abstract: The conductance quantization and shot noise below the first conductance plateau ${G}_{0}=2{e}^{2}/h$ are measured in a quantum point contact fabricated in a GaAs/AlGaAs tunnel-coupled double quantum well. From the conductance measurement, we observe a clear quantized conductance plateau at $0.5{G}_{0}$ and a small minimum in the transconductance at $0.7{G}_{0}$. Spectroscopic transconductance measurement reveals three maxima inside the first diamond, thus suggesting three minima in the dispersion relation for electric subbands. Shot noise measurement shows that the Fano factor behavior is consistent with this observation. We propose a model that relates these features to a wave-number directional split subband due to a strong Rashba spin-orbit interaction that is induced by the center barrier potential gradient of the double-layer sample.

Abstract: Conductance measurements of quantum point contacts (QPCs) reveal an anomalous plateau in the conductance at roughly 0.7 x ^ , just before a fully transmitting ID channel is available. Past experiments have built a consensus that this so-called "0.7 structure" is related to electron spin and electron-electron interaction, but the detailed description remains controversial. We have performed measurements on two new kinds of devices which give new insight into the interactions of electrons in these clean quasi-lD systems. One new device allows us to measure the compressibility of the electrons in a QPC for different conduction modes. Comparison with density functional calculations give new information about the relative importance of interactions (including exchange) as the density in the QPC is depleted. The other device allows us to measure the local density of states (dos) in the QPC as we tunnel directly into the constriction. Deviations from the ID dos would help to develop a more complete picture of the transport through a QPC.

Q1. What are the contributions in "Anticrossing of spin-split subbands in quasi-one-dimensional wires" ?

In this paper, it was shown that crossings of opposite-spin 1D subbands resemble magnetic phase transitions at zero dc source-drain bias, but display anticrossings at high dc bias.