Controlling the near-surface superfluid density in underdoped YBa2Cu3O6+x by photo-illumination

Stilp, E.; Suter, A.; Prokscha, T.; Salman, Z.; Morenzoni, E.; Keller, H.; Pahlke, Patrick; Hühne, Ruben; Bernhard, C.; Liang, Ruixing; Hardy, W. N.; Bonn, D. A.; Baglo, Jordan; Kiefl, R. F.

doi:10.1038/srep06250

Cited by 14 publications

(5 citation statements)

References 39 publications

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“…2. To illuminate the samples, either LEDs or solid-state lasers are available [7,25,26]. For illumination with blue light, we use either a LED source with λ = 405 nm (Bluepoint, Hönle AG, Gräfeling, Germany) or a diode pumped solid-state laser with λ = 457 nm.…”

Section: Methodsmentioning

confidence: 99%

Direct Observation of Hole Carrier-Density Profiles and Their Light-Induced Manipulation at the Surface ofGe

et al. 2020

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We demonstrate that, by using low-energy positive muon (μ +) spin spectroscopy as a local probe technique, the profiles of free charge carriers can be directly determined in the accumulation-depletion surface regions of p-or n-type Ge wafers. The detection of free holes is accomplished by measuring the effect of the interaction of the free carriers with the μ + probe spin on the observable muon spin polarization. By tuning the energy of the low energy μ + between 1 and 20 keV, the near-surface region between 10 and 160 nm is probed. We find hole carrier depletion and electron accumulation in all samples with doping concentrations up to the 10 17 cm −3 range, which is opposite to the properties of cleaved Ge surfaces. By illumination with light, the hole carrier density in the depletion zone can be manipulated in a controlled way. Depending on the used light wavelength λ, this change can be persistent (λ = 405, 457 nm) or nonpersistent (λ = 635 nm) at temperatures less than 270 K. This difference is attributed to the different kinetic energies of the photoelectrons. Photoelectrons generated by red light do not have sufficient energy to overcome a potential barrier at the surface to be trapped in empty surface acceptor states. Compared to standard macroscopic transport measurements our contactless local probe technique offers the possibility of measuring carrier depth profiles and manipulation directly. Our approach may provide important microscopic information on a nanometer scale in semiconductor device studies.

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Section: Methodsmentioning

confidence: 99%

Direct Observation of Hole Carrier-Density Profiles and Their Light-Induced Manipulation at the Surface ofGe

et al. 2020

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show abstract

“…2. To illuminate the samples, either LEDs or solid state lasers are available [7,24,25]. For illumination with blue light we used either a LED source with λ = 405 nm (Bluepoint, Hönle AG, Gräfeling, Germany) or a diode pumped solid state laser with λ = 457 nm.…”

Section: Methodsmentioning

confidence: 99%

Direct observation of hole carrier density profiles and their light induced manipulation at the surface of Ge

Prokscha,

Chow,

Salman

et al. 2019

Preprint

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We demonstrate that, by using low-energy positive muon (µ + ) spin spectroscopy as a local probe technique, the profiles of free charge carriers can be directly determined in the accumulation/depletion surface regions of p-or n-type Ge wafers. The detection of free holes is accomplished by measuring the effect of the interaction of the free carriers with the µ + probe spin on the observable muon spin polarization. By tuning the energy of the low-energy µ + between 1 keV and 20 keV the near-surface region between 10 nm and 160 nm is probed. We find hole carrier depletion and electron accumulation in all samples with doping concentrations up to the 10 17 /cm 3 range, which is opposite to the properties of cleaved Ge surfaces. By illumination with light the hole carrier density in the depletion zone can be manipulated in a controlled way. Depending on the used light wavelength λ this change can be persistent (λ = 405, 457 nm) or non-persistent (λ = 635 nm) at temperatures < 270 K. This difference is attributed to the different kinetic energies of the photo-electrons. Photoelectrons generated by red light do not have sufficient energy to overcome a potential barrier at the surface to be trapped in empty surface acceptor states. Compared to standard macroscopic transport measurements our contact-less local probe technique offers the possibility of measuring carrier depth profiles and manipulation directly. This new approach may provide important microscopic information on a nanometer scale in semiconductor device studies.

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“…11 is a way of a model-independent B-vs-z mapping. It has been demonstrated that subtle effects can, indeed, be measured by measuring the effects of photopersistent conductivity on Meissner screening in YBa 2 Cu 3 O 6+x (Stilp et al, 2014a), as well as the effects of gold nano-particle doping in YBa 2 Cu 3 O 7−δ , leading to increased Meissner screening (Stilp et al, 2014b). Kiefl et al (2010) measured the anisotropy of the London penetration depth in YBa 2 Cu 3 O 7−δ single crystals, which allows separating the contribution of the superconducting chains present in this compound.…”

Section: Frontiers In Electronic Materialsmentioning

confidence: 99%

SRF material research using muon spin rotation and beta-detected nuclear magnetic resonance

Junginger,

Laxdal,

MacFarlane

et al. 2024

Front. Electron. Mater

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Muon spins precess in transverse magnetic fields and emit a positron preferentially in the spin direction at the instant of decay, enabling muon spin rotation (μSR) as a precise probe of local magnetic fields in matter. μSR has been used to characterize superconducting radio-frequency (SRF) materials since 2010. At TRIUMF, a beam of 4.2 MeV μ+ is implanted at a material-dependent depth of approximately 150 μm. A dedicated spectrometer was developed to measure the field of first vortex penetration and pinning strength in SRF materials in parallel magnetic fields of up to 300 mT. A low-energy beam available at PSI implants μ+ at variable depth in the London layer allowing for direct measurements of the London penetration depth from which other material parameters relevant for SRF applications, such as the lower critical field and the superheating field, can be calculated. Beta-detected nuclear magnetic resonance (β-NMR) is a technique similar to low-energy μSR using beams of low-energy β radioactive ions. With a recent upgrade, it is capable of detecting the penetration of parallel magnetic vortices, depth resolved with nanometer resolution at applied fields of up to 200 mT. In this paper, we review the impact and capabilities of these techniques for SRF research.

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Controlling the near-surface superfluid density in underdoped YBa2Cu3O6+x by photo-illumination

Cited by 14 publications

References 39 publications

Direct Observation of Hole Carrier-Density Profiles and Their Light-Induced Manipulation at the Surface ofGe

Direct Observation of Hole Carrier-Density Profiles and Their Light-Induced Manipulation at the Surface ofGe

Direct observation of hole carrier density profiles and their light induced manipulation at the surface of Ge

SRF material research using muon spin rotation and beta-detected nuclear magnetic resonance

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