| dc.description.abstract | Magnets are materials that have a wide range of uses and have very high commercial and technological value. The most important areas of use are information storage systems. However, the information storage size is limited by the superparamagnetic size (or Quantum size effect) (10-100nm). Below this limit, information cannot be stored permanently due to free fluctuations in magnetization. In the other part, the quantum size effect was overcome with the discovery of molecules containing several metal ions that exhibit magnetic properties similar to nanoscale magnetic particles. Such polynuclear metal complexes that exhibit superparamagnetic-like properties are called "Single Molecule Magnetics (TMM)". In 1993, the first TMM was discovered by Gatteschi et al with the molecule Mn12-ac ([Mn12O12(O2CCH3COO)16(H2O)4]*2CH3COOH*4H2O) known as "Mn12". Many new TMMs have been produced since this discovery. For example, Fe8, Fe4, Ni4, Mn3, Mn4, Mn6Cr, Mn2Ni3, [(Pc)2Ln]--(Ln=Tb, Dy, Ho, Er, Tm or Yb), Sr2CoO4-Perovskite, DySc2N@C80-fulleren, V3 , V4 , V15. Single molecule magnets, quantum tunneling features, drug carrier systems, molecular machine elements, environmentally friendly, low energy and high efficiency new generation magnetic cooler systems, high resolution imaging systems, very high information storage and high capacity and fast quantum computing systems. It has become the center of attention scientifically, commercially and technologically due to its usage potential in the field. Therefore, in our project proposal, Mn12-ac single molecule magnet will be modeled using Effective Field Theory (EAT) and quantum tunneling properties of magnetization will be examined in detail. EAT, developed by Takahito KANEYOSHI, consists of single (spin-1/2, 1, 3/2, 2) and multiple (spin- (1 / 2,1), (1 / 2,3 / 2), (2, 3/2)) in modeling magnetic spin systems (such as nanowires, nanotubes, nanoparticles) and obtaining magnetic (ferromagnetic, antiferromagnetic, paramagnetic, diamagnetic, type II superconductivity) and thermodynamic (susceptibility, specific-heat and internal energy) properties of these systems. is a successful theory used. However, single molecule magnets are singular (such as spin-1/2, 1, 3/2, 2) and multiple (mixed; spin- (1 / 2,1), (1 / 2,3 / 2), (2, 3/2)) Although it consists of magnetic elements with spin, finite and nano-dimensional, in the literature, only one study has been reported by Yıldız et al. in which V15 single molecule magnet is modelled and investigated quantum tunneling properties by spin-1/2. Therefore, in our project, Mn12-ac TMM consisting of multi (4 spin-3/2 (Mn+4) and 8 spin-2 (Mn+3)) spin transition metals will be modeled using EAT, and the dependence of quantum tunneling properties on temperature (MT), external magnetic field (MH) and spin orientation will be studied in detail. | en_US |
