High-Field Paramagnetic Meissner Effect in Ga-Implanted Single Crystal

Abstract

We report on dc magnetization data collected from a modified superficial pinning potential YBa 2 Cu 3 O 7-δ single crystal with the goal of checking the majority contribution of the magnetic flux compression scenario to the high-field paramagnetic Meissner effect (HFPME). The additional superficial pinning centers were introduced at the YBa 2 Cu 3 O 7-δ [YBCO(Ga)] single crystal surface by Ga ion beam bombardment. The field-cooled warming (M FCW (T)), field-cooled cooling (M FCC (T)), and zero-field-cooled (M ZFC (T)) dc magnetizations were recorded, while magnetic fields H up to 50 kOe were applied parallel to the single crystal c-axis. M FCW (T) and M FCC (T) data show the usual superconductor diamagnetic response to H <;5 kOe. In contrast, when 5 kOe ≤ H ≤ 50 kOe was applied, M FCW (T) and M FCC (T), particularly for T≪T irr (H) (magnetic irreversibility temperature), become paramagnetic. The magnetic-field-dependent paramagnetic behavior of M FCW (T) and M FCC (T) is the physical signature of HFPME in superconductor materials. We contrast the HFPME observed to the YBCO(Ga) sample with that observed to a not irradiated YBa 2 Cu 3 O 7-δ (YBCO) single crystal. We suggest that the enhancement of superficial pinning potential collaborates definitely to the strengthening of the magnetic flux compression scenario and consequently to the reinforcement of the HPME in YBa 2 Cu 3 O 7-δ single crystals.