[1] Air Univ, Dept Phys, Funct Mat Lab, PAF Complex E-9, Islamabad, Pakistan
[2] PINSTECH, Polymer Composite Grp, Directorate Sci, PO Nilore, Islamabad, Pakistan
[3] Cardiff Univ, Sch Engn, Magnet & Mat Res Grp, Cardiff CF24 3AA, Wales
[4] Cardiff Univ, Sch Phys & Astron, Cardiff CF24 3AA, Wales