Supplementary material
Biomolecular ion detection using high-temperature
superconducting MgB2 strips
N. Zen,1,* H. Shibata,2 Y. Mawatari,3 M. Koike,1 and M. Ohkubo4
1
National Institute of Advanced Industrial Science and Technology (AIST), Research Institute of
Instrumentation Frontier (RIIF), Tsukuba, Ibaraki 305-8568, Japan
2
NTT Basic Research Laboratories, NTT Corporation, Atsugi, Kanagawa 243-0198, Japan
3
National Institute of Advanced Industrial Science and Technology (AIST), Electronics and Photonics
Research Institute (ESPRIT), Tsukuba, Ibaraki 305-8568, Japan
4
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Innovation Arena
Headquarters (TIA), Tsukuba, Ibaraki 305-8568, Japan
*
Address correspondence to: n.zen@aist.go.jp
The procedure to determine the LTspice parameters (L, on, Ron)
In order to obtain the proper output pulse of the LTspice circuit simulation to fit the
experimental waveform (Fig. 1(b) in the manuscript), we have to determine three free
parameters; the strip inductance L, the switching resistance Ron, and the duration time
on of the Ron. However, it is possible to determine these parameters independently each
other. First, the inductance L was determined by the exponential decay of the
experimental waveform, where the decay time is expressed by decay = L / Rload, that is
resulted in L = 30 nH. The LTspice simulated output pulses for different Ron and on are
shown in Fig. S1(a) and (b), respectively. Obviously, the rise time of the pulse is not
affected by different Ron. Only on is critical for the rise time and we can determine the
value from the experimental waveform. Because the experimental rise time (370 ps) is
within the upper limit of the time response of the preamplifier (180 ps), we can
determine on with an error of several tens of ps due to the round shape of the pulse top
caused by the limited bandwidth of the preamplifier (black dots in Fig. 1(b) in the
manuscript). Finally, Ron is determined by the experimental pulse height.
Figure S1. LTspice simulated output pulse for different switching resistance Ron (a) and
different duration time on (b). The vertical dashed line in (a) is the eye guide.
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TDGL simulation results assuming the different initial hot spot diameter (2r0 = 50 nm)
and the different hot spot duration time of duration = 2600 (39 ps)
Figure S2(a) and (b) are the TDGL simulation results by assuming the initial hot
spot diameter of 2r0 = 50 nm which is a quarter of the value in the manuscript. As
shown, both the spatial distribution of the normal current density jn (a) and the output
voltage Vout (b) are not affected by the initial hot spot diameter.
On the other hand, when 10 times smaller duration time of the hot spot is assumed,
the TDGL results differ significantly. Especially, the output pulse shape in Fig. S2(d) is
totally different from the experimental one. In conclusion, the initial hot spot diameter
doesn’t affect the TDGL results significantly and the assumed hot spot duration time of
duration = 26000 (390 ps) is consistent with the experimental results.
Figure S2. TDGL results assuming the different initial hot spot diameter of 2r0 = 50 nm are
shown in (a) (red line) and (b) (blue line) with the TDGL results of 2r0 = 200 nm (black dashed
line): (a) the spatial distribution of the normalized normal current density along the longitudinal
direction of the strip (x-axis) when the temperature reaches its highest value and (b) TDGL
output voltage with the experimental pulse (gray dots). TDGL results using different hot spot
duration time of 2600 (39 ps) with the hot spot diameter of 2r0 = 200 nm are shown in (c) and
(d).
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