The possibility of half metallic behavior has been investigated in Co2Mn1-xCrxSi and Co2MnxTi1-xAl thin films prepared by DC magnetron sputtering. Structural, magnetic and transport properties have been studied, particularly with a view to understanding the role of disorder on these properties. The growth conditions for deposition of these films on glass substrate without any additional buffer layer were optimized by using Co 2MnSi as the starting material. Crystallographic order in the films improved with increased substrate temperature and films grown at a temperature of 773K were found to exhibit the ordered L21 structure. Ferromagnetic order in the films also improved with increasing substrate temperature. A saturation magnetization (MS) value of 1061emu/cc, close to the MS value of bulk Co2MnSi, was obtained for the film deposited at 773K. Based on these optimized conditions, thin films of quaternary Co2Mn1-xCrxSi (0≤x≤ 1) Heusler alloy were prepared. High resolution transmission electron microscopy images of films showed granular morphologies, crystalline growth, and an ordered L21 structure in compositions with x≤0.6. For higher Cr concentrations (x>0.6), secondary phases started to appear and crystallinity was lost for x=1 composition. The Co2CrSi composition was found to possess disordered A2 structure and the desired L21 ordered phase was not obtained presumably due to the known instability of the desired phase. Magnetization measurements showed that for x≤0.2 magnetization values followed the Slater-Pauling rule, while for 0.2<x≤0.6 the MS values fell short of the theoretically predicted values. This decrease in saturation magnetization was explained in terms of Co-Cr antisite disorder present in these films. The values of Curie temperature were observed to decrease with increase in Cr concentration. For compositions with x>0.2 the enhancement of the Co-Cr antisite disorder also manifested itself in the decrease in the spin wave stiffness co-efficient and a sign change of the temperature coefficient of resistivity (at x>0.6). A resistivity minimum, observed at low temperatures (in metallic compositions) and the crossover from metallic to semiconducting type resistivity with increasing x were explained as originating mainly in the antisite disorder. These effects were explained in the light of Kaveh and Mott’s model of disorder leading to weak localization. For compositions with x≤0.6, the low temperature resistivity could be explained as arising from electron-electron interactions and due to two magnon scatterings. The latter is considered as an indicator for half metallic ferromagnetism. Both the onset temperatures as well as the temperature range for the half metallic features were observed to decrease with increasing x. In the other quaternary Heusler alloy Co2MnxTi1-xAl (0≤x≤ 1) thin film series all the compositions exhibited B2 type structure due to the effects of antisite disorder. The values of saturation magnetization increased with increasing Mn content in the films and were in general agreement with the values obtained using the Slater-Pauling rule. The general trend of magnetization in these thin films, as noted for others half metals, was describable as that of a Heisenberg ferromagnet at low temperature and an itinerant ferromagnet at higher temperatures. Electrical resistivity as a function of temperature showed a change from a metallic type behavior for x≤0.25 to a semiconducting type for x>0.25. At lower temperatures (T<25K) metallic compositions in this quaternary series also showed the presence of a resistivity minimum. The resistivity behavior above the low T upturn in metallic compositions followed a dependence that was explained in terms of electron-electron scattering and one magnon scattering. The expected half-metallic behavior was not clearly evident in this series, presumably being destroyed by the presence of Co antisite disorder within the B2-type structure, as has been predicted by first principle calculations. Finally, magnetoresistance measurements were performed on various compositions in Co2Mn1-xCrxSi series at temperatures below and above the resistivity minimum and the results were found consistent with the low field transport being strongly affected by spin polarized intergrain tunneling.
ڈاکٹرمولوی عبدالحق افسوس ہے پچھلے مہینے ڈاکٹر مولوی عبدالحق نے۹۲برس کی عمر میں مری میں انتقال کیا اورکراچی میں دفن ہوئے۔وہ غالباً علی گڑھ کے سب سے پرانے طالب علم تھے جنھوں نے سرسید احمد خاں،مولانا شبلی اورمولانا حالی اوراُس زمانہ کے دوسرے اکابر علم وادب سے استفادہ کیااوراُن کی صحبتوں اورمجلسوں سے فیض پایا تھا۔وہ۱۸۷۱ء میں ضلع میرٹھ کے ایک قصبہ ہاپوڑ میں پیداہوئے۔یہاں مڈل تک تعلیم پائی، پھر علی گڑھ چلے آئے اوریہاں سے۱۸۹۴ء میں بی۔اے کاامتحان پاس کیا، اس کے بعد حیدرآباد منتقل ہوگئے جہاں اُن کی زندگی کے بہترین ایام بسرہوئے۔ ایک اسکول کے ہیڈ ماسٹر مقرر ہوئے پھر انسپکٹر آف اسکولز کے عہدے پرفائز ہوئے۔اُس سے ترقی کی تواورنگ آبادکالج کے پرنسپل بنائے گئے۔اس کے بعد مولوی وحیدالدین سلیم کاانتقال ہواتواُن کی جگہ جامعۂ عثمانیہ میں اردو کے پروفیسر مقررہوئے۔موصوف جہاں اورجس حیثیت میں رہے اپنی لیاقت و قابلیت،حسن کارگردگی اورفرض شناسی کے باعث نمایاں اور ممتازہوکررہے لیکن قدرت نے جس اصل کام کے لیے پیداکیا تھا اورجس کے باعث انھیں بڑی شہرت اورعظمت نصیب ہوئی وہ ابھی تکمیل کے لیے اُن کے واسطے چشم براہ تھا۔چنانچہ جب وہ انسپکٹر آف اسکولز تھے انہی دنوں(۱۹۱۲ء) میں انجمن ترقی اردو کے سیکرٹری منتخب ہوئے۔انجمن اب تک محمڈن ایجوکیشنل کانفرنس کی ایک شاخ کی حیثیت رکھتی تھی لیکن مولوی عبدالحق صاحب نے اس کواتنی ترقی دی کہ وہ جلد ہی ایک مستقل انجمن بن گئی اوراس کی سرگرمیوں کاحلقہ وسیع ترہوتا چلا گیا۔ انجمن کے سیکرٹری منتخب ہونے سے لے کر اپنی زندگی کے آخری سانس تک موصوف نے اردو زبان وادب کی ہمہ جہتی خدمات جس محنت و استقلال، عزم وہمت اورایثارو قربانی کے ساتھ کم وبیش ایک نصف صدی تک انجام دی ہیں وہ صرف اردو زبان وادب کے حلقوں میں نہیں بلکہ تاریخ کے بڑے لوگوں کی صف میں جگہ دینے...
According to Islam, all the rules of ḥalāl and ḥarām are made easy and appropriate to the nature, because the maker of these rules knows each and every thing of human needs. Therefore, acting upon the teaching of Islam is so easy and simple for man. It is not work of everybody but it is responsibility of scholars and jurists to make and work on the rules, their limits prescribed in Islam.
This study was comparative study of teaching practices and maladaptive behaviors of the students of three
armed forces colleges. In which both the methods qualitative and quantitative were used. The major purpose
of this study was to compare the teaching practices in three armed forces colleges and find out most common
teaching practices.
The study was also focused on comparison of maladaptive behaviours of the students and find out most
common maladaptive behaviours of secondary level students. Efforts were also made to find out the reasons
and possible solutions of those behaviours. Researcher has selected three armed forces colleges.
The study focused on secondary level students and teachers. Target population for this study was seven
hundred and ninety nine students. Total three hundred and sixty students were selected from the target
population, among them one hundred and eighty were males and one hundred and eighty females. All
teachers (sixty six) who were teaching at secondary level in three armed forces colleges. Researcher has
designed two separate questionnaires for students and teachers. SPSS software was used to analyze the data.
Statistical techniques mean difference, frequency distribution; one way ANOVA, t-test and chi square were
used to examine the data. Analysis of variance was used to find out significant difference between teaching
practices, t-test was used to find out gender differences and chi square was used to find out significant
differences between maladaptive behaviors of the students.
Main findings indicated that there were significant differences in teaching practices in three armed forces
colleges at secondary level.
It was concluded that behaviors like bullying, fighting, abusing, disrespect, irregular, whispering, talking
during lecture etc. were common in the students of armed forces colleges, but significant differences were
found in these behaviors, fighting, refusal to follow instruction, annoying other children, paying attention to
something else, interruption etc. The results also indicated significant differences in the opinion of male and
female students. The findings of the research will be equally important for the teachers, parents and
administrators of secondary schools.