ملک عرب:
محل وقوع: براعظم ایشیاء کے جنوب مغرب میں واقع ملک عرب کے تین اطراف سمندر اور چوتھی طرف خشکی ہے ۔ مغرب میں بحیرہ قلزم ہے جو مکہ معظمہ سے مغربی جانب تقریباََ ستتر (۷۷) کلو میٹر کے فاصلہ پر ہے ۔اس کے علاوہ مغرب میں آبنائے سویز اور بحیرہ روم ہے ۔ مشرق میں خلیج فارس اور عمان ‘ جنوب میں بحرہند اور اس کے شمال میں شام و عراق اور شمال سے جنوب تک ایک سلسلہ کوہ پھیلا ہو ا ہے‘ جسے جبل السراۃ کہتے ہیں ‘ شمال میں یہ شام اور فلسطین کے پہاڑوں سے جا ملتا ہے ۔ اس سلسلہ کو جگہ جگہ سے وادیاں قطع کرتی ہیں ۔ سلسلہ جبال السراۃ کو توریت میں سلسلہ کو ہ فاران کا نام دیا گیا ہے ۔ ( سیرت النبی اعلان نبوت سے پہلے ۔ٖص۲۰)جغرافیہ کے ماہرین نے اس ملک کو آٹھ حصوں میں تقسیم کیا ہے ۔ جن میں سے ایک حجاز ہے ۔ چونکہ ’’تہامہ ‘‘ اور ’’ نجد ‘‘ کے درمیان حاجز ہے جو تہا مہ اور نجد کو الگ کرتا ہے اس لیے ملک کے اس حصہ کو حجاز کہتے ہیں ۔ حجاز کا زیادہ حصہ بنجر اور بے آب وگیاہ ہے جسے قرآن مجید نے ’’ وادی غیر ذی زرع‘‘ کہا ہے ۔اس میں صدیوں سے موجود (عرب کا قدیم شہر مکہ )یا بکہ ایک تجارتی مرکز تھا ۔ یمن ،شام اور حبشہ کے مابین تجارتی قافلوں کی گزر گاہ پر واقع تھا ۔ یہا ں کے باشندے بھی خوب تجارت کرتے تھے ۔ یمن اور حبشہ کی مصنوعات اور پیداوار خرید لاتے اور انہیں مصر اور شام کے بازاروں میں جا کر فروخت کرتے ۔وہ بصری ٰاور دمشق کے میلوں سے بھی سامان خرید لاتے اوراس کے بدلے میں اپنا سامان فروخت کرتے تھے ۔موسم گرما...
‘A great man’, says Justice Oliver Wendell, Jr, ‘represents a great ganglion in the nerves of society, or to vary the figure, a strategic point in the campaign of history, and part of his greatness consists in being there’. (italic ours). And Maulana Muhammad Ali was one such nerve-centre in Indo-Muslim society during the second and third decades of the twentieth century. Indeed, he was one such strategic point in the onward march of Indo-Muslim politics that eventually found culmination and crystallization in the emergence of Pakistan. Actually no one else represented the tone, tenor and temper of the romanticist, Khilafatist era (in the 1910s and 1920s) as he did in his hectic life, his revolutionary activities his numerous discomfitures, and in his tragic death. Whether he led a hectic life, whether he took recourse to a revolutionary path, or whether he goaded himself to die a tragic death outside the frontiers of his motherland cataclysmically, in whatever he did, he, consciously or unconsciously, carried forward the campaign of Indo-Muslim history: the redemption of Islam in India and abroad. In other words, he stood, above all, for an honourable existence for Muslims in India and in the rest of the troubled Muslim world in the existential crisis that convulsed Muslim India and that world.
This thesis is mainly focused on synthesis and characterization of (magnetic) nanostructures in the form of multilayers and magnetic oxides thin films for spintronics applications. Exchange bias phenomenon which has a critical role in ferromagnetic/antiferromagnetic multilayer system was studied experimentally with a theoretical understanding of very recent model of exchange bias namely York Model. Standard IrMn and CoFe multilayer system (Si/Cu/IrMn/CoFe/Ta) was fabricated using High Target Utilization Sputtering (HiTUS) to study various aspects of exchange bias. Effect of Mn doping showed a decrease in the blocking temperature. Chemical reaction of Mn at the interface and diffusion of Cu from the under layer in IrMn layer were considered to be cause of this decrease. Training effect in exchange coupled IrMn and CoFe multilayer thin films was investigated for varying grain size that was controlled during the fabrication process through bias voltage. It was observed that smallest grains gave rise to a larger training effect as larger anti-ferromagnetic grain volumes give rise to thermally stable bias fields and consequently smaller training effects. The result is found reproducible and in agreement with the literature. The effects of nucleation were also studied. It was determined that nucleation arises from both sample shape effects and the process used to cut the sample. The obtained results showed that sample edge roughness leads to a distribution of nucleation fields and hence changes the shape of the hysteresis loop. It was concluded that the best way to cut samples of nucleation controlled materials is by cracking for the application in spintronics devices. Second part of the study was about Ni and Co doped TiO 2 diluted magnetic semiconductors thin films grown by Aerosol Assisted Chemical Vapor Deposition (AACVD). AACVD method was adopted for synthesizing these films due to certain advantages over other chemical routes. Further, synthesis routes may vary various properties and there are only a handful reports in the literature in which AACVD method ixwas employed to synthesize diluted magnetic oxides. Ni and Co doped TiO2 films were prepared at 450 C and 650 C respectively with Argon as a carries gas. XRD, FESEM and RBS were carried out to see phase, morphology, and stoichiometry and film thickness. Magnetic properties of the films were investigated using SQUID. Ni and Co doping resulted in ferromagnetism in TiO 2 at room temperature attributed to the formation of Bound Magnetic Polaron (BMP).