Spin Degree of Freedom in the nu =1 Bilayer Electron System Investigated via Nuclear Spin Relaxation

TL;DR

This study measures nuclear spin relaxation in a bilayer electron system near nu=1, revealing that electron spin fluctuations persist across different quantum phases, challenging previous assumptions of spin freezing.

Contribution

It provides new insights into electron spin dynamics in bilayer systems, showing continuous spin fluctuations across quantum Hall and compressible states.

Findings

1/T_1 increases from QH to compressible state

Spin fluctuations are present in both QH and compressible states

Electron spin degree of freedom is not fully frozen in these states

Abstract

The nuclear-spin-relaxation rate 1/T_1 has been measured in a bilayer electron system at and around total Landau level filling factor nu =1. The measured 1/T_1, which probes electron spin fluctuations, is found to increase gradually from the quantum Hall (QH) state at low fields through a phase transition to the compressible state at high fields. Furthermore, 1/T_1 in the QH state shows a small but noticeable increase away from nu =1. These results demonstrate that, as opposed to common assumption, the electron spin degree of freedom is completely frozen neither in the QH nor compressible states.