Effect of Al Doping on the Irreversible Magnetization of MgB2 Single Crystals

Effect of Al Doping on the Irreversible Magnetization of MgB2 Single Crystals

We studied the temperature and the eld dependences of the irreversibility elds Hirr and the critical current density Jc of Mg1-xAlxB2 single crystals for x up to 0.2. The magnetic investigation revealed that the values and the eld dependences of Jc and Hirr were enhanced for x = 0.1, indicating a stronger pinning due to Al doping. On the other hand, for the heavily-Al-doped sample (x = 0.2), Jc and Hirr were reduced compared to the values for pure MgB2. We also found that the anisotropy of Hirr (= Hab irr/Hc /irr) increased with increasing Al doping, which may be due to a weakening of the inter-plane coupling as Al is substituted for Mg.

We studied the temperature and the eld dependences of the irreversibility elds Hirr and the critical current density Jc of Mg1-xAlxB2 single crystals for x up to 0.2. The magnetic investigation revealed that the values and the eld dependences of Jc and Hirr were enhanced for x = 0.1, indicating a stronger pinning due to Al doping. On the other hand, for the heavily-Al-doped sample (x = 0.2), Jc and Hirr were reduced compared to the values for pure MgB2. We also found that the anisotropy of Hirr (= Hab irr/Hc /irr) increased with increasing Al doping, which may be due to a weakening of the inter-plane coupling as Al is substituted for Mg.