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Robertson IO, Scholten SC, Singh P, Healey AJ, Meneses F, Reineck P, Abe H, Ohshima T, Kianinia M, Aharonovich I, Tetienne JP. Detection of Paramagnetic Spins with an Ultrathin van der Waals Quantum Sensor. ACS Nano 2023. [PMID: 37406158 DOI: 10.1021/acsnano.3c01678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/07/2023]
Abstract
Detecting magnetic noise from small quantities of paramagnetic spins is a powerful capability for chemical, biochemical, and medical analysis. Quantum sensors based on optically addressable spin defects in bulk semiconductors are typically employed for such purposes, but the 3D crystal structure of the sensor inhibits sensitivity by limiting the proximity of the defects to the target spins. Here we demonstrate the detection of paramagnetic spins using spin defects hosted in hexagonal boron nitride (hBN), a van der Waals material that can be exfoliated into the 2D regime. We first create negatively charged boron vacancy (VB-) defects in a powder of ultrathin hBN nanoflakes (<10 atomic monolayers thick on average) and measure the longitudinal spin relaxation time (T1) of this system. We then decorate the dry hBN nanopowder with paramagnetic Gd3+ ions and observe a clear T1 quenching under ambient conditions, consistent with the added magnetic noise. Finally, we demonstrate the possibility of performing spin measurements, including T1 relaxometry using solution-suspended hBN nanopowder. Our results highlight the potential and versatility of the hBN quantum sensor for a range of sensing applications and make steps toward the realization of a truly 2D, ultrasensitive quantum sensor.
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Affiliation(s)
- Islay O Robertson
- School of Science, RMIT University, Melbourne, Victoria 3001, Australia
| | - Sam C Scholten
- School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Priya Singh
- School of Science, RMIT University, Melbourne, Victoria 3001, Australia
| | - Alexander J Healey
- School of Science, RMIT University, Melbourne, Victoria 3001, Australia
- School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Fernando Meneses
- School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Philipp Reineck
- School of Science, RMIT University, Melbourne, Victoria 3001, Australia
- ARC Centre of Excellence for Nanoscale BioPhotonics, RMIT University, Melbourne, Victoria 3001, Australia
| | - Hiroshi Abe
- National Institutes for Quantum Science and Technology (QST), 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
| | - Takeshi Ohshima
- National Institutes for Quantum Science and Technology (QST), 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
- Department of Materials Science, Tohoku University, Sendai, 980-8579, Japan
| | - Mehran Kianinia
- School of Mathematical and Physical Sciences, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
- ARC Centre of Excellence for Transformative Meta-Optical Systems, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - Igor Aharonovich
- School of Mathematical and Physical Sciences, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
- ARC Centre of Excellence for Transformative Meta-Optical Systems, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
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Healey AJ, Rahman S, Scholten SC, Robertson IO, Abrahams GJ, Dontschuk N, Liu B, Hollenberg LCL, Lu Y, Tetienne JP. Varied Magnetic Phases in a van der Waals Easy-Plane Antiferromagnet Revealed by Nitrogen-Vacancy Center Microscopy. ACS Nano 2022; 16:12580-12589. [PMID: 35866839 DOI: 10.1021/acsnano.2c04132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Interest in van der Waals materials often stems from a desire to miniaturize existing technologies by exploiting their intrinsic layered structures to create near-atomically thin components that do not suffer from surface defects. One appealing property is an easily switchable yet robust magnetic order, which is only sparsely demonstrated in the case of in-plane anisotropy. In this work, we use widefield nitrogen-vacancy (NV) center magnetic imaging to measure the properties of individual flakes of CuCrP2S6, a multiferroic van der Waals magnet known to exhibit weak easy-plane anisotropy in the bulk. We chart the crossover between the in-plane ferromagnetism in thin flakes down to the trilayer and the bulk behavior dominated by a low-field spin-flop transition. Further, by exploiting the directional dependence of NV center magnetometry, we are able to observe an instance of a predominantly out-of-plane ferromagetic phase near zero field, in contrast with our expectation and previous experiments on the bulk material. We attribute this to the presence of surface anisotropies caused by the sample preparation process or exposure to the ambient environment, which is expected to have more general implications for a broader class of weakly anisotropic van der Waals magnets.
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Affiliation(s)
- Alexander J Healey
- School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Sharidya Rahman
- School of Engineering, College of Engineering and Computer Science, Australian National University, Canberra, ACT 2601, Australia
| | - Sam C Scholten
- School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Islay O Robertson
- School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
- School of Science, RMIT University, Melbourne, VIC 3001, Australia
| | - Gabriel J Abrahams
- School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
- School of Science, RMIT University, Melbourne, VIC 3001, Australia
| | - Nikolai Dontschuk
- School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Boqing Liu
- School of Engineering, College of Engineering and Computer Science, Australian National University, Canberra, ACT 2601, Australia
| | - Lloyd C L Hollenberg
- School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Yuerui Lu
- School of Engineering, College of Engineering and Computer Science, Australian National University, Canberra, ACT 2601, Australia
- Centre for Quantum Computation and Communication Technology, School of Engineering, The Australian National University, Canberra, ACT 2601, Australia
| | - Jean-Philippe Tetienne
- School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
- School of Science, RMIT University, Melbourne, VIC 3001, Australia
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Healey AJ, Bansi D, Dhanjal MK, Blunt D, Dawson P, Buchanan GN. Colorectal stenting: a bridge to both Caesarean section and elective resection in malignant large-bowel obstruction in pregnancy: a multidisciplinary first. Colorectal Dis 2011; 13:e248-9. [PMID: 20874794 DOI: 10.1111/j.1463-1318.2010.02429.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- A J Healey
- Department of Colorectal Surgery, Imperial College NHS Trust, Charing Cross Hospital, London, UK
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Abstract
A consequence of employing coherent detection methods in medical ultrasound imaging systems is the occurrence of interference effects in the received echo field, which produce the speckle artefact. Speckle can severely degrade the information content of the image, and its efficient removal from ultrasound pulse-echo images is the focus of a number of research projects. Traditionally, the approach towards speckle reduction in pulse-echo images has been based on two classes of technique, either employing some form of spatial/frequency compounding or a data (image) filter. Both approaches have inherent shortcomings, and two alternative techniques are suggested here: 'local frequency diversity' and 'frequency differencing'. These algorithms deterministically identify where speckle occurs, and correct for speckle only within short, localized, corrupted segments of the A-line. This provides the potential for real-time implementation. Simulated and clinical in vivo images have been obtained, and the capabilities of the alternative speckle reduction algorithms are assessed against the more conventional approaches.
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Affiliation(s)
- F Forsberg
- Department of Medical Engineering and Physics, King's College School of Medicine and Dentistry, Dulwich Hospital, London, UK
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