Table 1 Fit parameters for the seven spin-triplet SQUID samples measured.

The first two characters in the sample name, for example, “2A,” refer to the chip, while the final number refers to the specific device on the chip. (Each chip contains four SQUIDs.) The value 2n is the total number of [Pd/Co] bilayers in the central F layer. The SQUID oscillation curves were fit to standard SQUID theory, as shown in Fig. 3 for device 2A-4, while keeping the total inductance fixed to the nominal value of 9 pH. The last column of the table shows that the flux shifts of the SQUID oscillation curves between the two magnetic states are very close to ½Φ0, which corresponds to a phase shift of π for one of the two junctions in the SQUID. The fits also provide approximate values of the critical currents in the two junctions, Ic1 and Ic2. (The uncertainties in the values of Ic1 and Ic2 derived from the fits appear to be too small, as the value of Ic2 for the nonswitching junction appears to change between the two magnetic states. We believe that this is a generic feature of fits to SQUID data for SQUIDs in the low-inductance limit, βL << 1.) The data for all samples except 2A-4 can be found in the Supplementary Materials.

SQUID name2nStateIc1 (μA)Ic2 (μA)ΔΦshift0
2A-1416.65 ± 0.084.20 ± 0.080.491 ± 0.005
26.90 ± 0.124.18 ± 0.12
2A-2414.09 ± 0.144.02 ± 0.140.542 ± 0.004
25.66 ± 0.105.61 ± 0.10
2A-3414.53 ± 0.124.56 ± 0.120.480 ± 0.004
26.88 ± 0.074.67 ± 0.07
2A-4414.56 ± 0.046.16 ± 0.040.509 ± 0.003
27.30 ± 0.157.08 ± 0.15
3A-3610.80 ± 0.300.79 ± 0.300.519 ± 0.010
21.99 ± 0.021.34 ± 0.02
4A-1610.60 ± 0.333.16 ± 0.330.618 ± 0.005
21.45 ± 0.033.87 ± 0.03
4A-2611.32 ± 0.042.41 ± 0.040.493 ± 0.004
23.01 ± 0.011.61 ± 0.01