Superconducting quantum interference devices (SQUIDs) can be used to detect weak magnetic fields and have traditionally been the most sensitive magnetometers available. However, because of their relatively large effective size (on the order of 1 µm)1,2,3,4, the devices have so far been unable to achieve the level of sensitivity required to detect the field generated by the spin magnetic moment (μB) of a single electron5,6. Here we show that nanoscale SQUIDs with diameters as small as 46 nm can be fabricated on the apex of a sharp tip. The nano-SQUIDs have an extremely low flux noise of 50 nΦ0 Hz−1/2 and a spin sensitivity of down to 0.38 μB Hz−1/2, which is almost two orders of magnitude better than previous devices2,3,7,8. They can also operate over a wide range of magnetic fields, providing a sensitivity of 0.6 μB Hz−1/2 at 1 T. The unique geometry of our nano-SQUIDs makes them well suited to scanning probe microscopy, and we use the devices to image vortices in a type II superconductor, spaced 120 nm apart, and to record magnetic fields due to alternating currents down to 50 nT.
Subscribe to Journal
Get full journal access for 1 year
only $15.58 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Cleuziou, J-P., Wernsdorfer, W., Bouchiat, V., Ondarçuhu, T. & Monthioux, M. Carbon nanotube superconducting quantum interference device. Nature Nanotech. 1, 53–59 (2006).
Koshnick, N. C. et al. A terraced scanning superconducting quantum interference device susceptometer with submicron pickup loops. Appl. Phys. Lett. 93, 243101 (2008).
Nagel, J. et al. Superconducting quantum interference devices with submicron Nb/HfTi/Nb junctions for investigation of small magnetic particles. Appl. Phys. Lett. 99, 032506 (2011).
Veauvy, C., Hasselbach, K. & Mailly, D. Scanning µ-superconduction quantum interference device force microscope. Rev. Sci. Instrum. 73, 3825–3830 (2002).
Rugar, D., Budakian, R., Mamin, H. J. & Chui, B. W. Single spin detection by magnetic resonance force microscopy. Nature 430, 329–332 (2004).
Degen, C. L. & Home, J. P. Scanning probes: cold-atom microscope shapes up. Nature Nanotech. 6, 399–400 (2011).
Hao, L. et al. Measurement and noise performance of nano-superconducting-quantum-interference devices fabricated by focused ion beam. Appl. Phys. Lett. 92, 192507 (2008).
Finkler, A. et al. Self-aligned nanoscale SQUID on a tip. Nano Lett. 10, 1046–1049 (2010).
Clarke, J. & Braginski, A. I. (eds) The SQUID Handbook: Fundamentals and Technology of SQUIDs and SQUID Systems Vol. I (Wiley VCH, 2006).
Kirtley, J. R. Fundamental studies of superconductors using scanning magnetic imaging. Rep. Prog. Phys. 73, 126501 (2010).
Foley, C. P. & Hilgenkamp, H. Why nanoSQUIDs are important: an introduction to the focus issue. Supercond. Sci. Technol. 22, 064001 (2009).
Troeman, A. G. P. et al. NanoSQUIDs based on niobium constrictions. Nano Lett. 7, 2152–2156 (2007).
Lam, S. K. H., Clem, J. R. & Yang, W. A nanoscale SQUID operating at high magnetic fields. Nanotechnology 22, 455501 (2011).
Mandal, S. et al. The diamond superconducting quantum interference device. ACS Nano 5, 7144–7148 (2011).
Tesche, C. D. & Clarke, J. DC SQUID: noise and optimization. J. Low Temp. Phys. 29, 301–331 (1977).
Likharev, K. K. Superconducting weak links. Rev. Mod. Phys. 51, 101–159 (1979).
Van Harlingen, D. J., Koch, R. H. & Clarke, J. Superconducting quantum interference device with very low magnetic flux noise energy. Appl. Phys. Lett. 41, 197–199 (1982).
Awschalom, D. D. et al. Low‐noise modular microsusceptometer using nearly quantum limited dc SQUIDs. Appl. Phys. Lett. 53, 2108–2110 (1988).
Levenson-Falk, E. M., Vijay, R., Antler, N. & Siddiqi, I. A dispersive nanoSQUID magnetometer for ultra-low noise, high bandwidth flux detection. Supercond. Sci. Technol. 26, 055015 (2013).
Ketchen, M. B. et al. Design, fabrication, and performance of integrated miniature SQUID suseptometers. IEEE Trans. Magn. 25, 1212–1215 (1989).
Huber, M. E. et al. Gradiometric micro-SQUID susceptometer for scanning measurements of mesoscopic samples. Rev. Sci. Instrum. 79, 053704 (2008).
Budker, D. & Romalis, M. Optical magnetometry. Nature Phys. 3, 227–234 (2007).
Waldherr, G. et al. High-dynamic-range magnetometry with a single nuclear spin in diamond. Nature Nanotech. 7, 105–108 (2012).
Nusran, N. M., Momeen, M. U. & Gurudev Dutt, M. V. High-dynamic-range magnetometry with a single electronic spin in diamond. Nature Nanotech. 7, 109–113 (2012).
Maletinsky, P. et al. A robust scanning diamond sensor for nanoscale imaging with single nitrogen-vacancy centres. Nature Nanotech. 7, 320–324 (2012).
Rondin, L. et al. Nanoscale magnetic field mapping with a single spin scanning probe magnetometer. Appl. Phys. Lett. 100, 153118 (2012).
Finkler, A. et al. Scanning superconducting quantum interference device on a tip for magnetic imaging of nanoscale phenomena. Rev. Sci. Instrum. 83, 073702 (2012).
Tilbrook, D. L. NanoSQUID sensitivity for isolated dipoles and small spin populations. Supercond. Sci. Technol. 22, 064003 (2009).
Bending, S. J. Local magnetic probes of superconductors. Adv. Phys. 48, 449–535 (1999).
Matsuda, T. et al. Oscillating rows of vortices in superconductors. Science 7, 2136–2138 (2001).
Auslaender, O. M. et al. Mechanics of individual isolated vortices in a cuprate superconductor. Nature Phys. 5, 35–39 (2009).
Schwarz, A., Liebmann, M., Pi, U. H. & Wiesendanger, R. Real space visualization of thermal fluctuations in a triangular flux-line lattice. New J. Phys. 12, 033022 (2010).
Huber, M. et al. DC SQUID series array amplifiers with 120 MHz bandwidth. IEEE Trans. Appl. Supercond. 11, 4048–4053 (2001).
This work was supported by the European Research Council (ERC advanced grant) and by the Minerva Foundation with funding from the Federal German Ministry for Education and Research. Y.A. acknowledges support by the Azrieli Foundation and by the Fonds Québécois de la Recherche sur la Nature et les Technologies. M.H. acknowledges support from the Weston Visiting Professorship programme. E.Z. acknowledges support from the US–Israel Binational Science Foundation (BSF).
The authors declare no competing financial interests.
About this article
Cite this article
Vasyukov, D., Anahory, Y., Embon, L. et al. A scanning superconducting quantum interference device with single electron spin sensitivity. Nature Nanotech 8, 639–644 (2013). https://doi.org/10.1038/nnano.2013.169
Superconductor Science and Technology (2020)
High-transition-temperature nanoscale superconducting quantum interference devices directly written with a focused helium ion beam
Applied Physics Letters (2020)
SQUID-on-tip with single-electron spin sensitivity for high-field and ultra-low temperature nanomagnetic imaging
Nano Letters (2020)