Tunneling gap collapse and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>v</mml:mi><mml:mo>=</mml:mo><mml:mn>2</mml:mn><mml:mn /></mml:math>quantum Hall state in a bilayer electron system

Geer, S. J.; Davies, A. G.; Barnes, C. H. W.; Zolleis, K. R.; Simmons, M. Y.; Ritchie, D. A.

doi:10.1103/physrevb.66.045318

Cited by 7 publications

(3 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Theory [3,4,5,6,7,8] suggested a canted antiferromagnetic (CAF) state, where spins in the two layers have antiparallel in-plane components and parallel out-of-plane components. Transport [9,10,11] and capacitance [12] measurements have also shown a phase transition. Recently, a nuclear spin relaxation measurement [13] has revealed a gapless spin excitation mode (Goldstone mode) indicative of the in-plane antiferromagnetic order [4,5].…”

mentioning

confidence: 99%

NMR Evidence for Spin Canting in a Bilayerν=2Quantum Hall System

2007

View full text Add to dashboard Cite

We investigate the electron spin states in the bilayer quantum Hall system at total Landau level filling factor ν = 2 exploiting current-pumped and resistively detected NMR. The measured Knight shift, KS, of 75 As nuclei reveals continuous variation of the out-of-plane electronic spin polarization between nearly full and zero as a function of density imbalance. Nuclear spin relaxation measurements indicate a concurrent development of an in-plane spin component. These results provide direct information on the spin configuration in this system and comprise strong evidence for the spin canting suggested by previous experiments.Bilayer quantum Hall (QH) systems have found rich electronic phases that emerge as a consequence of the interplay between different degrees of freedom. In particular, at total Landau level filling factor ν = 2, where two of the four lowest Landau levels split by the Zeeman and interlayer tunnel couplings are occupied, the competing spin and layer degrees of freedom lead to rich magnetic phases. When the interlayer coupling is weak, the system behaves like two independent single-layer ν = 1 systems, resulting in a ferromagnetic (F) ground state with spins in each layer aligned parallel to the magnetic field by intralayer interactions and the weak Zeeman coupling. When the tunneling is strong, on the other hand, the interlayer antiferromagnetic coupling leads to a spin-singlet (SS) ground state resembling the single-layer ν = 2 state. Inelastic light scattering [1,2] has shown a mode softening indicating the existence of another state between these two states. Theory [3,4,5,6,7,8] suggested a canted antiferromagnetic (CAF) state, where spins in the two layers have antiparallel in-plane components and parallel out-of-plane components. Transport [9,10,11] and capacitance [12] measurements have also shown a phase transition. Recently, a nuclear spin relaxation measurement [13] has revealed a gapless spin excitation mode (Goldstone mode) indicative of the in-plane antiferromagnetic order [4,5]. Although these experiments are consistent with the CAF state, direct information on the spin configuration, such as the spin polarization P z , has not been reported.Nuclear magnetic resonance (NMR) is a powerful probe for P z because the hyperfine interaction between electron and nuclear spins shifts the nuclear resonant frequency by the Knight shift K S , which is proportional to P z . In two-dimensional electron systems (2DESs), a weak signal resulting from a small number of nuclei in contact with the 2DES restricts standard NMR measurements to multiple-quantum-well systems [14,15,16,17]. Recently, a K S measurement on a single-layer system has been achieved [18], where the NMR signal from nuclei in a quantum well (QW) is resistively detected. However, the method cannot be used to measure K S in a welldeveloped QH state, where the longitudinal resistance R xx is vanishingly small regardless of the nuclear spin polarization.In this Letter, we report the measurement of K S in the bilayer ν = 2 QH state usin...

show abstract

mentioning

confidence: 99%

NMR Evidence for Spin Canting in a Bilayerν=2Quantum Hall System

2007

View full text Add to dashboard Cite

show abstract

“…Recently the phase diagram in the σ − n T plane was constructed [17], where n T is the total electron density and σ is the density imbalance between the two layers. Though capacitance spectroscopy [18] as well as magnetotransport measurements [19,20,21,22] were carried out, experimental studies on the CAF phase remain less systematic than theoretical works. This paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

Magnetotransport study of the canted antiferromagnetic phase in bilayerν=2quantum Hall state

et al. 2006

View full text Add to dashboard Cite

Magnetotransport properties are investigated in the bilayer quantum Hall state at the total filling factor ν = 2. We measured the activation energy elaborately as a function of the total electron density and the density difference between the two layers. Our experimental data demonstrate clearly the emergence of the canted antiferromagnetic (CAF) phase between the ferromagnetic phase and the spin-singlet phase. The stability of the CAF phase is discussed by the comparison between experimental results and theoretical calculations using a Hartree-Fock approximation and an exact diagonalization study. The data reveal also an intrinsic structure of the CAF phase divided into two regions according to the dominancy between the intralayer and interlayer correlations.

show abstract

“…They also have observed softening signals indicating second-order phase transitions [12]. Subsequently, an unambiguous evidence of the CAF phase was obtained through capacitance spectroscopy as well as magnetotransport measurements [13,14,15,16,17,18].…”

Section: Introductionmentioning

confidence: 93%

The study of Goldstone modes in ν = 2 bilayer quantum Hall systems

et al. 2012

View full text Add to dashboard Cite

At the filling factor ν=2, the bilayer quantum Hall system has three phases, the spin-ferromagnet phase, the spin singlet phase and the canted antiferromagnet (CAF) phase, depending on the relative strength between the Zeeman energy and interlayer tunneling energy. We present a systematic method to derive the effective Hamiltonian for the Goldstone modes in these three phases. We then investigate the dispersion relations and the coherence lengths of the Goldstone modes. To explore a possible emergence of the interlayer phase coherence, we analyze the dispersion relations in the zero tunneling energy limit. We find one gapless mode with the linear dispersion relation in the CAF phase. PACS. 73.21.-b Collective excitations in nanoscale systems -73.43.Nq Phase transitions quantum Hall effects

show abstract

Tunneling gap collapse andv=2quantum Hall state in a bilayer electron system

Cited by 7 publications

References 24 publications

NMR Evidence for Spin Canting in a Bilayerν=2Quantum Hall System

NMR Evidence for Spin Canting in a Bilayerν=2Quantum Hall System

Magnetotransport study of the canted antiferromagnetic phase in bilayerν=2quantum Hall state

The study of Goldstone modes in ν = 2 bilayer quantum Hall systems

Contact Info

Product

Resources

About