Erratum: Light-induced hyperfine<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">Ga</mml:mi><mml:mprescripts /><mml:none /><mml:mn>69</mml:mn></mml:mmultiscripts></mml:math>shifts in semi-insulating GaAs observed by optically polarized NMR [Phys. Rev. B<b>74</b>, 153201 (2006)]

Ramaswamy, Kannan; Mui, Stacy; Hayes, Sophia E.

doi:10.1103/physrevb.75.249903

Cited by 6 publications

(14 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…To further obtain the sensitivity and selectivity needed to isolate signals of local, nanoscale features from the bulk signal of a macroscopic sample, we combined the POWER approach with methods for optical NMR (ONMR). By using both optical nuclear polarization (ONP) (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) and optical detection (2-4, 6, 7, 9-13), ONMR provides the sensitivity needed for measurements on single epitaxial structures with selectivity for those sites that experience hyperfine coupling to photoexcited electrons in III-V semiconductors.…”

mentioning

confidence: 99%

“…The utility of ONMR in probing excited states has been long noted (3)(4)(5)13) and used to explore electrostatics in quantum wells (16,17), dots (10), and bulk materials (14,15), but at a spectral resolution of no better than several kilohertz, set by many-body dipolar coupling between spins. Here, achieving resolution down to a few hertz, we demonstrate separate isolation of single-nucleus properties as the source of coherent spin evolution.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Imaging quantum confinement with optical and POWER (perturbations observed with enhanced resolution) NMR

Kempf

Miller

Weitekamp

2008

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The nanoscale distributions of electron density and electric fields in GaAs semiconductor devices are displayed with NMR experiments. The spectra are sensitive to the changes to the nuclear-spin Hamiltonian that are induced by perturbations delivered in synchrony with a line-narrowing pulse sequence. This POWER (perturbations observed with enhanced resolution) method enhanced resolution up to 10 3 -fold, revealing the distribution of perturbations over nuclear sites. Combining this method with optical NMR, we imaged quantum-confined electron density in an individual AlGaAs/GaAs heterojunction via hyperfine shifts. Fits to the coherent evolution and relaxation of nuclei within a hydrogenic state established one-to-one correspondence of radial position to frequency. Further experiments displayed the distribution of photoinduced electric field within the same states via a quadrupolar Stark effect. These unprecedented high-resolution distributions discriminate between competing models for the luminescence and support an excitonic state, perturbed by the interface, as the dominant source of the magnetically modulated luminescence.GaAs ͉ hyperfine or Knight shift ͉ Stark effect ͉ H-band photoluminescence I maging electron distributions and the electrostatic potentials that govern their transfer is a longstanding goal in diverse fields. Spin or charge transfer defines function in systems for photovoltaic and photosynthetic energy capture, ion channels, enzyme catalysis, spintronics, and molecular and nanoscale electronics. Success in imaging nanoscale electronic properties can lead to mechanistic understanding and provide guidelines to tune device performance or to modify natural systems for specialized applications. With its atomic-scale capabilities for nondestructive, noninvasive spectroscopy and imaging, NMR seems well suited to such characterization. However, NMR of solids is hampered by broad spectral lines because of static interactions that prevent measurement of small differences between sites that might otherwise reveal local electronic features with atomic detail.Here, we present a general method whereby solid-state NMR surmounts this challenge and then apply it to image distributions of spin density and electric (E) field within an electronic state with dimensions (Ϸ10 nm) distributed over Ϸ10 5 nuclei. The POWER (perturbations observed with enhanced resolution) NMR approach, encodes small responses to a sample perturbation that is switched in synchrony with an NMR multiple-pulse line-narrowing sequence. The sequence removes the otherwise obscuring clutter of static spin interactions to yield a spectrum dominated by the desired perturbation with up to 3 orders-ofmagnitude resolution enhancement. To further obtain the sensitivity and selectivity needed to isolate signals of local, nanoscale features from the bulk signal of a macroscopic sample, we combined the POWER approach with methods for optical NMR (ONMR). By using both optical nuclear polarization (ONP) (1-15) and optical detection (2-4, 6, 7, 9-13), O...

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

Imaging quantum confinement with optical and POWER (perturbations observed with enhanced resolution) NMR

Kempf

Miller

Weitekamp

2008

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…This latter finding is not discussed further here, but one can refer to these references for additional information. 3,16 The asymmetry in the signal intensity with respect to the helicity of the laser-which is especially prominent below the bandedge--is also captured in our simulations. The magnitude of the OPNMR signal is greater for σ + light than for σ − ., and the phenomena reflect the z-projection of average electron spin polarization 〈S z 〉 The asymmetry primarily arises due to the contribution of quasithermal equilibrium electron polarization.…”

Section: Resultsmentioning

confidence: 95%

“…This interaction results in an enhanced, polarized NMR signal; 2,3,13,14 the sign and magnitude of the resulting OPNMR signal therefore depends on the z-projection of the average electron spin polarization 〈S z 〉, created through optical pumping. 15 , 16 As such, OPNMR is inherently sensitive to the sign and magnitude of the electron spin polarization.…”

Section: Introductionmentioning

confidence: 99%

Experimental measurements of optically-pumped NMR (OPNMR) and spin polarization in bulk GaAs and GaAs/AlGaAs quantum wells

et al. 2014

Self Cite

View full text Add to dashboard Cite

Optically-pumped nuclear magnetic resonance (OPNMR) is a measurement scheme that utilizes optical pumping of conduction electrons within a semiconductor to polarize systems of nuclear spins to which they are coupled. The spectroscopic power of NMR techniques is brought to bear on these rare spin systems through enhancement of the nuclear spin polarization, here in direct-gap semiconductors such as bulk semi-insulating GaAs and GaAs/AlGaAs quantum wells. The nuclear spins act as reporters of the electron spins that are oriented during optical pumping with circularly polarized laser light, at specific photon energies. The effects of penetration depth of the laser in the sample can be understood when irradiating at energies less than the bandgap energy, as well as details of coupling to interband transitions originating from Landau levels at photon energies greater than the bandgap energy. We show that OPNMR is particularly sensitive to the sign of magnetization that results from light hole-to-conduction band transitions because the sign of magnetization is reversed when the light hole states in the valence band are accessed.

show abstract

“…The recombination time, τ e , was set to ≈ 10 ns [23] and the ratio τ e /T 1e was allowed to vary between 1.0 to 10.0 [46] as well providing a method to model the decay of laser intensity (and therefore Γ) as the laser penetrates into the sample [18].…”

Section: Simulations Of Opnmr Signalsmentioning

confidence: 99%

Modelling of OPNMR phenomena using photon energy-dependent 〈S〉 in GaAs and InP

Wheeler

Willmering

Sesti

et al. 2016

Journal of Magnetic Resonance

Self Cite

View full text Add to dashboard Cite

We have modified the model for optically-pumped NMR (OPNMR) to incorporate a revised expression for the expectation value of the z-projection of the electron spin, 〈S〉 and apply this model to both bulk GaAs and a new material, InP. This expression includes the photon energy dependence of the electron polarization when optically pumping direct-gap semiconductors in excess of the bandgap energy, E. Rather than using a fixed value arising from coefficients (the matrix elements) for the optical transitions at the k=0 bandedge, we define a new parameter, S(E). Incorporating this revised element into the expression for 〈S〉, we have simulated the photon energy dependence of the OPNMR signals from bulk semi-insulating GaAs and semi-insulating InP. In earlier work, we matched calculations of electron spin polarization (alone) to features in a plot of OPNMR signal intensity versus photon energy for optical pumping (Ramaswamy et al., 2010). By incorporating an electron spin polarization which varies with pump wavelength into the penetration depth model of OPNMR signal, we are able to model features in both III-V semiconductors. The agreement between the OPNMR data and the corresponding model demonstrates that fluctuations in the OPNMR intensity have particular sensitivity to light hole-to-conduction band transitions in bulk systems. We provide detailed plots of the theoretical predictions for optical pumping transition probabilities with circularly-polarized light for both helicities of light, broken down into illustrative plots of optical magnetoabsorption and spin polarization, shown separately for heavy-hole and light-hole transitions. These plots serve as an effective roadmap of transitions, which are helpful to other researchers investigating optical pumping effects.

show abstract

Erratum: Light-induced hyperfineGa69shifts in semi-insulating GaAs observed by optically polarized NMR [Phys. Rev. B74, 153201 (2006)]

Cited by 6 publications

References 0 publications

Imaging quantum confinement with optical and POWER (perturbations observed with enhanced resolution) NMR

Imaging quantum confinement with optical and POWER (perturbations observed with enhanced resolution) NMR

Experimental measurements of optically-pumped NMR (OPNMR) and spin polarization in bulk GaAs and GaAs/AlGaAs quantum wells

Modelling of OPNMR phenomena using photon energy-dependent 〈S〉 in GaAs and InP

Contact Info

Product

Resources

About