In fluxonics, superconducting technology of the future, the information bit is represented by fluxon, an elementary magnetic flux tube also known as the Abrikosov vortex. The design of superconductive devices will require the knowledge of its inertial mass, playing the same role here as effective electron mass in semiconducting electronics. Nevertheless, the fluxon mass is a particularly controversial issue. Its theoretical estimates are scattered over more than eight orders of magnitude and only two experiments existed prior to our experiment.
We have designed and developed a unique far-infrared (FIR) transmission setup capable of probing the circular dichroism, reflecting the different response of vortices for left- (LHCP, T-) and right-handed circular polarization (RHCP,T+), see figure 1. While at zero magnetic field transmittance is the same for both circular polarization states, in magnetic field transmittance for RHCP and LHCP clearly deviates.
We show that the theory of Kopnin and coworkers, extended to high-frequency response, reproduces our experimental data without any fitting parameter, see figure 2. All relevant parameters were obtained from DC resistivity measurement and from THz conductivity spectra measured by time-domain terahertz spectroscopy. Thus our results support the theory of the fluxon mass developed by Kopnin and Vinokur and that of the Magnus force reduction by the factor of Kopnin and Kravtsov. For YBa2Cu3O7−δ at 45 K, the Kopnin’s mass of the fluxon at zero-frequency limit amounts to 3 × 108 electron mass/cm.
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