Campbell penetration depth in low carrier density superconductor YPtBi

Magnetic penetration depth, lambda(m), was measured as a function of temperature and magnetic field in single crystals of low carrier density superconductor YPtBi by using a tunnel-diode oscillator technique. Measurements in zero DC magnetic field yield London penetration depth, lambda(L)(T), but in the applied field the signal includes the Campbell penetration depth, lambda(C)(T), which is the characteristic length of the attenuation of small excitation field, H-AC, into the Abrikosov vortex lattice due to its elasticity. Whereas the magnetic field dependent lambda(C) exhibit lambda(C) similar to B-p with p = 1/2 in most of the conventional and unconventional superconductors, we found that p approximate to 0.23 << 1/2 in YPtBi due to rapid suppression of the pinning strength. From the measured lambda(C)(T, H), the critical current density is j(c) approximate to 40 A/cm(2) at 75 mK. This is orders of magnitude lower than that of conventional superconductors of comparable T-c.

Automated summary

In this study, the magnetic penetration depth in single crystals of YPtBi superconductor was measured as a function of temperature and magnetic field. The results showed that the Campbell penetration depth and the critical current density were significantly influenced by the applied magnetic field. This research provides valuable data for the study of superconductors.