1301.1189 (R. Wölbing et al.)

Optimizing the spin sensitivity of grain boundary junction nanoSQUIDs --
towards detection of small spin systems with single-spin resolution    [PDF]

R. Wölbing, T. Schwarz, J. Nagel, M. Kemmler, D. Koelle, R. Kleiner

We present an optimization study for improving the spin sensitivity of nanoSQUIDs based on resistively shunted grain boundary Josephson junctions. In addition the dc SQUIDs contain a narrow constriction onto which a small magnetic particle can be placed with efficient coupling of its stray magnetic field to the SQUID loop. The separation of the location of optimum coupling from the junctions allows for an independent optimization of coupling and junction properties. Our analysis of the dependence of the flux noise of the SQUID and of the coupling of a magnetic particle on the geometric parameters of the SQUID layout shows that a spin sensitivity S_{\mu}^(1/2) of a few \mu_B/Hz^(1/2) should be feasible for optimized parameters, respecting technological constraints.

View original: http://arxiv.org/abs/1301.1189