Low-temperature “interaction field” and pinning efficiency in YBaCuO crystals with columnar defects

Abstract We determine the pinning efficiency η of columnar defects in YBaCuO crystals at low temperatures. At low pin densities (matching fields B Ф ≲1 Tesla), we find a single track η ∼ 1 2 for both; the continuous aligned tracks generated by irradiation with 1 Gev Au and globular splayed tracks generated by 0.58 GeV Sn ions. We conclude that the “interaction field” B ★ ( T ≈0) = η B Ф , which separates single-vortex and collective pinning regimes, is independent of the detailed nature of damage.