Resistively Detected Nuclear Magnetic Resonance in the Quantum Hall Regime: Possible Evidence for a Skyrme Crystal

Desrat, Wilfried; Maude, D. K.; Potemski, M.; Portal, J. C.; Wasilewski, Z. R.; Hill, G.

doi:10.1103/physrevlett.88.256807

Cited by 84 publications

(98 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast to the RDNMR spectrum with only a dip or a peak in R xx under the AC bias, 8 the DC counterpart shows a peak-dip line shape. Such a dispersive RDNMR signal has also been demonstrated in GaAs 2DEGs, [16][17][18][19][20] but the underlying mechanism remains obscure. Because the DC-related RDNMR signal is stronger than the AC signal in this sample, we therefore employ the DC current for the high-temperature RDNMR study.…”

mentioning

confidence: 99%

Resistively detected nuclear magnetic resonance via a single InSb two-dimensional electron gas at high temperature

Yang¹,

Liu

Nagase³

et al. 2011

Applied Physics Letters

View full text Add to dashboard Cite

We report on the demonstration of the resistively detected nuclear magnetic resonance (RDNMR) of a single InSb two-dimensional electron gas (2DEG) at elevated temperatures up to 4 K. The RDNMR signal of 115 In in the simplest pseudospin quantum Hall ferromagnet triggered by a large direct current shows a peak-dip line shape, where the nuclear relaxation time T 1 at the peak and the dip is different but almost temperature independent. The large Zeeman, cyclotron, and exchange energy scales of the InSb 2DEG contribute to the persistence of the RDNMR signal at high temperatures.

show abstract

mentioning

confidence: 99%

Resistively detected nuclear magnetic resonance via a single InSb two-dimensional electron gas at high temperature

Yang¹,

Liu

Nagase³

et al. 2011

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…As a consequence of the additional symmetry breaking, the 2D electron system supports spin waves which, contrary to the ferromagnetic spin wave, remain gapless in the presence of the magnetic field [13,14,15]. Both a jump in the specific heat and the very short T 1 observed away from ν=1 were interpreted as indirect consequences of the enhanced coupling between the nuclear spins and the electron system due to the gapless spin waves (Goldstone mode) of the Skyrme crystal [16,17,18].While most studies of Skyrmions have focused solely on their impact on electron spin polarization, no experiment has explored up to now the possibility of exploring Skyrmion interactions and the magnetic ground state of the 2DES near ν=1 by probing long-wavelength spin wave excitations. Measurements of spin wave excitation are especially valuable since they are expected to reflect the presence of a broken symmetry state arising from XY spin ordering [14].…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Soft Spin Wave nearν=1: Evidence for a Magnetic Instability in Skyrmion Systems

et al. 2008

View full text Add to dashboard Cite

The ground state of the two dimensional electron gas near ν=1 is investigated by inelastic light scattering measurements carried down to very low temperatures. Away from ν=1, the ferromagnetic spin wave collapses and a new low-energy spin wave emerges below the Zeeman gap. The emergent spin wave shows soft behavior as its energy increases with temperature and reaches the Zeeman energy for temperatures above 2 K. The observed softening indicates an instability of the two dimensional electron gas towards a magnetic order that breaks spin rotational symmetry. We discuss our findings in light of the possible existence of a Skyrme crystal.In condensed matter physics, the competition between distinct correlated electron ground states follows from a delicate interplay between dimensionality, strength of Coulomb interactions, and disorder. Correlated states may possess long range spin and/or charge order that breaks a symmetry that, in turn, has profound consequences on the nature of the low-energy excitation spectrum [1,2]. One well-known example of the relationship between broken-symmetry and elementary excitations is the isotropic ferromagnet. The broken rotational spin symmetry leads to appearance of gapless spin wave excitations, Goldstone modes, that are fluctuations of the spin density around the magnetization direction.The ground state of the two-dimensional (2D) electron gas at Landau level filling factor ν=1 is a special kind of itinerant ferromagnet, the quantum Hall ferromagnet, where all electrons occupy the lowest orbital Landau level and their spins are aligned along the external magnetic field. The quantum Hall ferromagnet supports collective excitations similar to ferromagnetic spin-waves with a gap given by the bare Zeeman energy E z [3,4]. The quantum Hall ferromagnet also has spin texture excitations built from Skyrmions [5,6], a concept used to describe the emergence of nuclear particles in the context of field theories of nuclear matter [7]. Skyrmions are topological objects which smoothly distort the ferromagnetic order in a vortex-like configuration. Each individual Skyrmion involves several flipped spins and is therefore not favored by the Zeeman energy. On the other hand because the exchange energy is large in quantum Hall systems, and it prefers locally aligned spins, Skyrmions are cheaper than single spin-flips for sufficiently low E z . The relevance of Skyrmions has been demonstrated by a wide range of experiments probing the spin polarization of the 2DES [8,9,10,11].Near ν=1 the interaction between Skyrmions may lock orientations of spin in the XY plane to favor the formation of a Skyrme crystal of electron spin orientation that breaks spin rotational symmetry about the magnetic field axis [12]. As a consequence of the additional symmetry breaking, the 2D electron system supports spin waves which, contrary to the ferromagnetic spin wave, remain gapless in the presence of the magnetic field [13,14,15]. Both a jump in the specific heat and the very short T 1 observed away from ν=1 were inter...

show abstract

“…The first candidate to think of is the electric quadrupole interaction. Samples with an intrinsic electric field gradient, caused for example by internal or external stress, exhibit multiple, evenly spaced resonances due to the electric quadrupole interaction [8,200]. However, this effect always leads to at least three resonances in the NMR response.…”

Section: Nmr Spectroscopy Of the Stripe Phasementioning

confidence: 99%

“…The Knight shift depends on both the spin polarization and the electron densityin general the electron spin density. Over the last years, this technique has been established as a reliable method to probe the electron spin polarization [9,158,159,200]. The downside of this method in its current form is that it is only applicable at filling factors where depends on the Zeeman energy.…”

Section: Chapter 4 Spin Polarization Of the 5 ⁄2 Statementioning

confidence: 99%

Spin and Charge Ordering in the Quantum Hall Regime

Frieß

2016

Springer Theses

View full text Add to dashboard Cite

Resistively Detected Nuclear Magnetic Resonance in the Quantum Hall Regime: Possible Evidence for a Skyrme Crystal

Cited by 84 publications

References 25 publications

Resistively detected nuclear magnetic resonance via a single InSb two-dimensional electron gas at high temperature

Resistively detected nuclear magnetic resonance via a single InSb two-dimensional electron gas at high temperature

Soft Spin Wave nearν=1: Evidence for a Magnetic Instability in Skyrmion Systems

Spin and Charge Ordering in the Quantum Hall Regime

Contact Info

Product

Resources

About