3136

2920

كارشناسي ارشد

فيزيك

اصفهان: دانشگاه صنعتي اصفهان، دانشكده فيزيك

1385

[ده]، 105، [II]ص.:مصور، جدول، شكل، نمودار

هادي اكبرزاده

مهدي صفاي اصفهاني

سعيد جلالي اسدآبادي

1396/10/27

كتابنامه

فيزيك

فيزيك

ID2920

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

AbstractThe rapid development of the today tedchnology motivated an extensive search for new materialswith new properties In this regard transition metal alloys are the focus of interest and investigationbecause these materials exhibit great variety of magnetic and structural properties In this thesis wehave investigated N ix Cr x alloy at di rent concentrations at x 0 25 0 250 0 375 0 500 0 625 0 750 0 875 by using the wien2k package this package performs electronic structure calculationsof solids within the framework of desity functional theory DFT The full potential linearized augment plane wave L APW lo method to solve the single particle kohn sham equation Crand Ni are the parent mettal this alloy have di rent ground states of Antiferromagnetic bcc andFerromagnetic fcc respectively Therefore mixing these metals could principle lead to severalstructural and magnetic orderings Hense our main work in this project was to nd the stabe crystallattice and magnetic state of each concentration In order to do this job we have applied severalpossible and reasonable structures based on bcc and fcc lattices magnetic order By calculationand comparing the total energy of these system we could identify the most stable state MMS ofeach composstions of Ni Cr alloy The calculated formation energies of MMS indicate that as it isexpected there are two phase transitions in this system The rst one is structural phase transition bcc to fcc that occures around x 0 22 and the second is a magnetic phase transition ferrimagneticorder to ferromagnetic order that take place between 0 625 and 0 750 Also the formation energy ofMMS shows that just in 0 6 0 78 x range formation energy is negative In Industry this range callednikrom In addition we found that the RKKY exchange is the dominant mechanism to interactions inthe bcc baced structures we observed that some of atomic moment in the fcc based structure havingsome types of antiferromagnetic orders vanishes It was attributed to the frusstration e ects andit seems that using noncollinear magnetid calculation changes this observation Another interstingfeature of our results was the observed half matallicity for N i0 75 Cr0 25 alloy This special propertyalong with its hifh magnetic and formation energy it is the most stable alloy encourage furtherconsiration of the this alloy as a possible condidate for spintronic application

هادي اكبرزاده

مهدي صفاي اصفهاني