Micron-sized Hall probes on a Si/SiGe heterostructure as a tool to study vortex dynamics in high-temperature superconducting crystals

Veen, R. G. van; Verbruggen, A. H.; Drift, E. van der; Radelaar, S.; Anders, S.; Jaeger, H. M.

doi:10.1063/1.1149666

Cited by 8 publications

(6 citation statements)

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“…More recently high sensitivity and spatial resolution have been achieved with GaAs/Al x Ga 1−x As heterojunction structures [79,80,81,82,83,84]. In addition, 250 nm sized scanning probes using GaSb/InAs/GaSb [83], and micron-scale Si/SiGe and InGaAs/InP Hall crosses have been characterized at low temperatures [85,86]. Hicks et al [87] have fabricated Hall bars as small as 85 nm on a side (see Fig.…”

Section: Hall Bar Microscopymentioning

confidence: 99%

“…More recently high sensitivity and spatial resolution have been achieved with GaAs/Al x Ga 1−x As heterojunction structures [79][80][81][82][83][84]. In addition, 250 nm sized scanning probes using GaSb/InAs/GaSb [83] and micrometerscale Si/SiGe and InGaAs/InP Hall crosses have been characterized at low temperatures [85,86]. Hicks et al [87] have fabricated Hall bars as small as 85 nm on a side (see figure 5) from GaAs/Al x Ga 1−x As heterojunction electron gas material, and estimate a field noise of 500 µT Hz −1/2 and a spin sensitivity of 1.2 × 10 4 µ B Hz −1/2 at 3 Hz and 9 K for sensors 100 nm on a side.…”

Section: Hall Bar Microscopymentioning

confidence: 99%

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Fundamental studies of superconductors using scanning magnetic imaging

Kirtley¹

2010

Rep. Prog. Phys.

150

115

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In this review I discuss the application of scanning magnetic imaging to fundamental studies of superconductors, concentrating on three scanning magnetic microscopies -scanning SQUID microscopy (SSM), scanning Hall bar microscopy (SHM), and magnetic force microscopy (MFM). I briefly discuss the history, sensitivity, spatial resolution, invasiveness, and potential future developments of each technique. I then discuss a selection of applications of these microscopies. I start with static imaging of magnetic flux: An SSM study provides deeper understanding of vortex trapping in narrow strips, which are used to reduce noise in superconducting circuitry. Studies of vortex trapping in wire lattices, clusters, and arrays of rings and nanoholes show fascinating ordering effects. The cuprate high-T c superconductors are shown to have predominantly d-wave pairing symmetry by magnetic imaging of the half-integer flux quantum effect. Arrays of superconducting rings act as a physical analog for the Ising spin model, with the half-integer flux quantum effect helping to eliminate one source of disorder in antiferromagnetic arrangements of the ring moments. Tests of the interlayer tunneling model show that the condensation energy available from this mechanism can not account for the high critical temperatures observed in the cuprates. The strong divergence in the magnetic fields of Pearl vortices allows them to be imaged using SSM, even for penetration depths of a millimeter. Unusual vortex arrangements occur in samples comparable in size to the coherence length. Spontaneous magnetization is not observed in Sr 2 RuO 4 , which is believed to have p x ± ip y pairing symmetry, although effects hundreds of times bigger than the sensitivity limits had been predicted. However, unusual flux trapping is observed in this superconductor. Finally, unusual flux arrangements are also observed in magnetic superconductors. I then turn to vortex dynamics: Imaging of vortices in rings of highly underdoped cuprates places limits on spin-charge separation in these materials. Studies of spontaneous generation of fluxoids upon cooling rings through the superconducting transition provide clues to dynamical processes relevant to the early development of the universe, while studies of vortex motion in cuprate grain boundaries allow the measurement of currentvoltage characteristics at the femtovolt scale for these technologically important defects. Scanning SQUID susceptometry allows the measurement of superconducting fluctuations on samples comparable in size to the coherence length, reveal stripes in susceptibility believed to be associated with enhanced superfluid density on the twin boundaries in the pnictide superconductor Co-doped Ba-122, and indicate the presence of spin-like excitations, which may be a source of noise in superconducting devices, in a wide variety of materials. Scanning magnetic microscopies allow the absolute value of penetration depths to be measured locally over a wide temperature range, providing clues to the symmetry of the ...

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Section: Hall Bar Microscopymentioning

confidence: 99%

Section: Hall Bar Microscopymentioning

confidence: 99%

Fundamental studies of superconductors using scanning magnetic imaging

Kirtley¹

2010

Rep. Prog. Phys.

150

115

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“…7 Micron-scale Si/ SiGe and InGaAs/ InP Hall crosses have been characterized at low temperature but have not been incorporated into scanning probes. 8,9 The Hall signal is V = I͑R offset + R H B z ͒, where B z is the average perpendicular field at the Hall cross, I is the drive current, R H =1/ne is the Hall coefficient ͑n is the 2D carrier density͒, and R offset is due to lithography imperfections or asymmetrical current flow. Useful systems offer low n ͑for large R H ͒ and high mobility ͑for higher conductance, reducing Johnson noise, and allowing higher drive current͒.…”

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confidence: 99%

Noise characteristics of 100nm scale GaAs∕AlxGa1−xAs scanning Hall probes

Hicks

Luan

Moler

et al. 2007

Applied Physics Letters

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The authors have fabricated and characterized GaAs/ Al x Ga 1−x As two-dimensional electron gas scanning Hall probes for imaging perpendicular magnetic fields at surfaces. The Hall crosses range from 85ϫ 85 to 1000ϫ 1000 nm 2 . They study low-frequency noise in these probes, especially random telegraph noise, and show that low-frequency noise can be significantly reduced by optimizing the voltage on a gate over the Hall cross. The authors demonstrate a 100 nm Hall probe with a sensitivity of 0.5 G / ͱ Hz ͑flux sensitivity of 0.25m⌽ 0 / ͱ Hz; spin sensitivity of 1.2 ϫ 10 4 B / ͱ Hz͒ at 3 Hz and 9 K.

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“…In recent years, several magnetic imaging tools emerged, like e.g. magnetic resonance force sensors [5], sensors based on nitrogen vacancy defects in diamond [6], and Hall [7] or SQUID type sensors [8]. Although the latter are one of the most sensitive devices for measuring magnetic flux, their usual optimization with respect of field sensitivity or current resolution leads to devices with dimensions of several m to mm and are therefore not well adapted to the task of measuring small spin systems.…”

Section: Introductionmentioning

confidence: 99%

Nearly quantum limited nanoSQUIDs based on cross-type Nb/AlO_x/Nb junctions

Schmelz

Zakosarenko²,

Schönau

et al. 2016

Supercond. Sci. Technol.

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We report on the development of nearly quantum limited SQUIDs with miniature pickup loop dimensions. The implemented high quality and low capacitance cross-type Nb/AlO x /Nb Josephson junctions offer large I C R N -products and therefore enable an exceptional low noise level of the SQUIDs. Devices with loop dimensions of 1 µm exhibit white flux noise levels as low as 45 n 0 /Hz 1/2 corresponding to an energy resolution  of about 1 h at 4.2 K, with h being Planck's constant. Moreover, the large usable voltage swings of the devices of about 300 µV allow highly sensitive and easy single-stage operation while exploring nearly the intrinsic noise of the SQUIDs, beneficial e.g. for sensor arrays in SQUID microscopy.

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Micron-sized Hall probes on a Si/SiGe heterostructure as a tool to study vortex dynamics in high-temperature superconducting crystals

Abstract: Weak localization and charge-carrier interaction effects in a two-dimensional hole gas in a germanium quantum well in a Si

Cited by 8 publications

References 10 publications

Fundamental studies of superconductors using scanning magnetic imaging

Fundamental studies of superconductors using scanning magnetic imaging

Noise characteristics of 100nm scale GaAs∕AlxGa1−xAs scanning Hall probes

Nearly quantum limited nanoSQUIDs based on cross-type Nb/AlO_x/Nb junctions

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Micron-sized Hall probes on a Si/SiGe heterostructure as a tool to study vortex dynamics in high-temperature superconducting crystals

Abstract: Weak localization and charge-carrier interaction effects in a two-dimensional hole gas in a germanium quantum well in a Si

Cited by 8 publications

References 10 publications

Fundamental studies of superconductors using scanning magnetic imaging

Fundamental studies of superconductors using scanning magnetic imaging

Noise characteristics of 100nm scale GaAs∕AlxGa1−xAs scanning Hall probes

Nearly quantum limited nanoSQUIDs based on cross-type Nb/AlOx/Nb junctions

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Nearly quantum limited nanoSQUIDs based on cross-type Nb/AlO_x/Nb junctions