Scanning SQUID susceptometers with sub-micron spatial resolution

Kirtley, J. R.; Paulius, L. M.; Rosenberg, Aaron; Palmstrom, Johanna C.; Holland, Connor M.; Spanton, Eric; Schiessl, Daniel; Jermain, Colin; Gibbons, Jonathan; Fung, YS; Huber, M. E.; Ralph, Daniel; Ketchen, M. B.; Gibson, Gerald W.; Moler, Kathryn A.

doi:10.1063/1.4961982

Cited by 100 publications

(90 citation statements)

References 34 publications

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“…We are interested in extending the use of ultra-thin YIG films to cryogenic temperatures, for example so that we can use scannning SQUID microscopy 19 to study the manipulation of YIG devices by spin-orbit torques.…”

Section: 18mentioning

confidence: 99%

Increased low-temperature damping in yttrium iron garnet thin films

et al. 2017

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We report measurements of the frequency and temperature dependence of ferromagnetic resonance (FMR) for a 15-nm-thick yttrium iron garnet (YIG) film grown by off-axis sputtering. Although the FMR linewidth is narrow at room temperature (corresponding to a damping coefficient α = (9.0 ± 0.2) ×10 −4 ), comparable to previous results for high-quality YIG films of similar thickness, the linewidth increases strongly at low temperatures, by a factor of almost 30. This increase cannot be explained as due to two-magnon scattering from defects at the sample interfaces.We argue that the increased low-temperature linewidth is due to impurity relaxation mechanisms that have been investigated previously in bulk YIG samples. We suggest that the low-temperature linewidth is a useful figure of merit to guide the optimization of thin-film growth protocols because it is a particularly sensitive indicator of impurities.

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Section: 18mentioning

confidence: 99%

Increased low-temperature damping in yttrium iron garnet thin films

et al. 2017

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“…The point-by-point scanning technique of SQUID magnetometers [2,3,24] provides high-ac-sensitivity 10 −6 Φ 0 = ffiffiffiffiffiffi Hz p (10-100× worse at dc) imaging at length scales from a few microns [24] to approximately 100 nm [2,3] and down to dilution refrigerator temperatures. [New SQUIDson-a-tip have achieved ac flux sensitivities of below 10…”

Section: Comparison To Other Techniquesmentioning

confidence: 99%

“…Quantum sensors comprised of nitrogen-vacancy (NV) color centers in diamond have joined scanning superconducting quantum-interference devices (SQUIDs) in advancing high-sensitivity magnetometry into the nanoscale regime [1][2][3]. Bose-Einstein condensates (BECs) have also been used for magnetometry [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Sensing Magnetic Fields with a Giant Quantum Wave

Fortágh

Günther

2017

Physics

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Microscopic imaging of local magnetic fields provides a window into the organizing principles of complex and technologically relevant condensed-matter materials. However, a wide variety of intriguing strongly correlated and topologically nontrivial materials exhibit poorly understood phenomena outside the detection capability of state-of-the-art high-sensitivity high-resolution scanning probe magnetometers. We introduce a quantum-noise-limited scanning probe magnetometer that can operate from room-to-cryogenic temperatures with unprecedented dc-field sensitivity and micron-scale resolution. The Scanning Quantum Cryogenic Atom Microscope (SQCRAMscope) employs a magnetically levitated atomic Bose-Einstein condensate (BEC), thereby providing immunity to conductive and blackbody radiative heating. The SQCRAMscope has a field sensitivity of 1.4 nT per resolution-limited point (approximately 2 μm) or 6 nT= ffiffiffiffiffiffi Hz p per point at its duty cycle. Compared to point-by-point sensors, the long length of the BEC provides a naturally parallel measurement, allowing one to measure nearly 100 points with an effective field sensitivity of 600 pT= ffiffiffiffiffiffi Hz p for each point during the same time as a point-by-point scanner measures these points sequentially. Moreover, it has a noise floor of 300 pT and provides nearly 2 orders of magnitude improvement in magnetic flux sensitivity (down to 10 −6 Φ 0 = ffiffiffiffiffiffi Hz p ) over previous atomic probe magnetometers capable of scanning near samples. These capabilities are carefully benchmarked by imaging magnetic fields arising from microfabricated wire patterns in a system where samples may be scanned, cryogenically cooled, and easily exchanged. We anticipate the SQCRAMscope will provide charge-transport images at temperatures from room temperature to 4 K in unconventional superconductors and topologically nontrivial materials.

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“…Nanoscale magnetic imaging is gaining interest in recent years in diverse fields of research and applications, including biological, chemical, and physical systems 1-3 . The quest for quantitative mapping of extremely weak local magnetic signals has driven development of very sensitive new techniques, including cold atom chips 4 , scanning nitrogen-vacancy diamond magnetometers 2,[5][6][7][8] , and scanning micro-and nano-superconducting quantum interference devices (SQUIDs) [9][10][11][12][13][14][15] . These tools have been employed for quantitative imaging of microscopic static and dynamic magnetic structures 6,[16][17][18][19][20] , current imaging 7,21,22 , and responses to local perturbations 23,24 .…”

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confidence: 99%

SQUID-on-tip with single-electron spin sensitivity for high-field and ultra-low temperature nanomagnetic imaging

et al. 2020

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Scanning nanoscale superconducting quantum interference devices (nanoSQUIDs) are of growing interest for highly sensitive quantitative imaging of magnetic, spintronic, and transport properties of low-dimensional systems. Utilizing specifically designed grooved quartz capillaries pulled into a sharp pipette, we have fabricated the smallest SQUID-on-tip (SOT) devices with effective diameters down to 39 nm. Integration of a resistive shunt in close proximity to the pipette apex combined with self-aligned deposition of In and Sn, have resulted in SOT with a flux noise of 42 n0Hz -1/2 , yielding a record low spin noise of 0.29 µBHz -1/2 . In addition, the new SOTs function at sub-Kelvin temperatures and in high magnetic fields of over 2.5 T. Integrating the SOTs into a scanning probe microscope allowed us to image the stray field of a single Fe3O4 nanocube at 300 mK. Our results show that the easy magnetization axis direction undergoes a transition from the (111) direction at room temperature to an in-plane orientation, which could be attributed to the Verwey phase transition in Fe3O4.

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Scanning SQUID susceptometers with sub-micron spatial resolution

Cited by 100 publications

References 34 publications

Increased low-temperature damping in yttrium iron garnet thin films

Increased low-temperature damping in yttrium iron garnet thin films

Sensing Magnetic Fields with a Giant Quantum Wave

SQUID-on-tip with single-electron spin sensitivity for high-field and ultra-low temperature nanomagnetic imaging

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