Effects of α-particle beam irradiation on superconducting properties of thin film MgB₂superconductors

Abstract

Superconducting properties of thin film MgB2 superconductors irradiated with 45 MeV -particle beam were studied. After the irradiation, enhancement of the critical current density and pinning force was observed, scaling close to strong pinning formula. Double logarithmic plots of the maximum pinning force density with irreversible magnetic field show a power law behavior close to carbon-doped MgB2 film or polycrystals. Variation of normalized pinning force density in the reduced magnetic field suggests scaling formulas for strong pinning mechanism like planar defects. We also observed a rapid decay of critical current density as the vortex lattice constant decreases, due to the strong interaction between vortices and increasing magnetic field. Table I. RESULTS AND DISCUSSIONWe show the irradiation effect on pinning properties and analyze the underlying physics.

Wetting Property Modification of Al2O3 by Helium Ion Irradiation: Effects of Beam Energy and Fluence on Contact Angle

“…By exploiting this nuclear reaction, the tuning of the wetting properties is expected to be intrinsically feasible if the hydrophilic oxide lattice is converted into elements that form hydrophobic functional groups. In contrast, He ion irradiation, which is being actively studied in the field of the clinic and material enhancement, − can broaden the scope of research by applying nuclear transmutation. Although several types of ions may be candidates for initiating a nuclear reaction, He ion irradiation has the advantage of obtaining hydrophobic functional groups, without generating radioactive nuclides with a long half-life.…”

Control of superconductivity in MgB2 by ion bombardment

“…While there have been many reports on radiation effects in MgB 2 [15][16][17][18][19][20][21][22][23][24][25][26], most have focused on the effects of either neutron irradiation [15][16][17][18][19] or bombardment with high-energy ions [22][23][24][25][26][27][28][29][30][31] that create intense electronic excitation along ion tracks, in the so-called swift heavy ion (SHI) regime. Interest in SHI irradiation of MgB 2 was stimulated by observations of a spectacular increase in J c in SHI-irradiated cuprate superconductors [11,12].…”

“…Here, SHI irradiation creates quasione-dimensional ion tracks that act as effective flux pinning centers. All attempts to replicate such a large J c increase in SHI-irradiated MgB 2 have been unsuccessful, and most have observed minimal radiation-induced changes to T c [22][23][24][25][26][27][28][29][30][31]. This failing is likely because amorphous ion tracks form along the trajectories of SHIs only in certain non-metallic materials systems [32], while elemental and binary metals (such as MgB 2 ) are not glass formers.…”

“…The remaining few reports [20,21,30,31,[34][35][36] on the response of MgB 2 to damage created by ions in the nuclear energy loss regime leave many fundamental questions unanswered. These include the damage buildup behavior and the role of irradiation conditions, and collision cascade density in particular.…”