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## Full-Text Articles in Physics

Quantum Monte Carlo Calculations Applied To Magnetic Molecules , Larry Paul Engelhardt

#### Quantum Monte Carlo Calculations Applied To Magnetic Molecules , Larry Paul Engelhardt

*Retrospective Theses and Dissertations*

In this dissertation, we have implemented a quantum Monte Carlo (QMC) algorithm, and have used it to perform calculations for a variety of finite Heisenberg spin systems. A detailed description of the QMC method has been provided, which is followed by applications of the method to various systems. These applications begin with a detailed analysis of the (calculated) equilibrium magnetization and magnetic susceptibility for a number of Heisenberg Hamiltonians. In particular, we have studied the dependence of these quantities on intrinsic spin s, and have quantified the approach to the classical (s → infinity) limit. These results are not specific to ...

Designing Of Metallic Photonic Structures And Applications , Yong-Sung Kim

#### Designing Of Metallic Photonic Structures And Applications , Yong-Sung Kim

*Retrospective Theses and Dissertations*

In this thesis our main interest has been to investigate metallic photonic crystal and its applications. We explained how to solve a periodic photonic structure with transfer matrix method and when and how to use modal expansion method. Two different coating methods were introduced, modifying a photonic structure's intrinsic optical properties and rigorous calculation results are presented;Two applications of metallic photonic structures are introduced. For thermal emitter, we showed how to design and find optimal structure. For conversion efficiency increasing filter, we calculated its efficiency and the way to design it.

Self Assembled Nano-Structures Of Pb On Si(111) Studied By Spa-Leed: Quantum Size Effect Driven Pb Islands And The "Devil's Staircase" , Michael Keith Yakes

#### Self Assembled Nano-Structures Of Pb On Si(111) Studied By Spa-Leed: Quantum Size Effect Driven Pb Islands And The "Devil's Staircase" , Michael Keith Yakes

*Retrospective Theses and Dissertations*

An important goal in present day surface science is to grow uniform sized self-assembled nanostructures. One system which has displayed a number of interesting surface structures is Pb grown on a Si(111) substrate. The first part of the thesis discusses the "Devil's Staircase" (DS) of linear phases studied with Scanning Tunneling Microscopy (STM) and Spot-Profile Analysis Low Energy Electron Diffraction (SPA-LEED). The DS is one of the outstanding predictions in theoretical physics and is expected to exist in systems with two competing interactions. It was found that at low temperatures (<120>K) over 15 different DS phases can be ...

Search For Multi-Photon Signatures Of A Higgs Boson In Ppbar Collisions At Sqrt(S) = 1.96 Tev , Oleksiy Vladimirovich Atramentov

#### Search For Multi-Photon Signatures Of A Higgs Boson In Ppbar Collisions At Sqrt(S) = 1.96 Tev , Oleksiy Vladimirovich Atramentov

*Retrospective Theses and Dissertations*

We have performed a search for a fermiophobic Higgs boson in tri-photon events. The study has been performed on 0.83 fb-1 of data collected with the DZero detector at the Tevatron collider, the world's highest energy accelerator. The study was motivated by the recent phenomenological study that suggests that at presently attained energies and statistics new Higgs production mechanisms become experimentally accessible. All backgrounds were estimated from the data in a self consistent manner. We observed zero tri-photon events and expected 0.5 +/- 0.2 from the Standard Model processes. Therefore, we set 95% CL upper limit on ...

Coupled Magnetic And Structural Transitions In High-Purity Dy And Gd[Subscript 5]Sb[Subscript X]Ge[Subscript 4-X] , Alexander S. Chernyshov

#### Coupled Magnetic And Structural Transitions In High-Purity Dy And Gd[Subscript 5]Sb[Subscript X]Ge[Subscript 4-X] , Alexander S. Chernyshov

*Retrospective Theses and Dissertations*

We undertook a detailed study of a single crystal of dysprosium metal, which is a classical example of a system where magnetic and crystallographic sublattices can be either coupled or decoupled from one another. Magnetocaloric effect, magnetization, ac magnetic susceptibility, and heat capacity of high purity single crystals of dysprosium have been investigated over broad temperature and magnetic field intervals with the magnetic field vector parallel to either the a- or c-axes of the crystal. Notable differences in the behavior of the physical properties when compared to Dy samples studied in the past have been observed between 110 K and ...

Soft-Lithographical Fabrication Of Three-Dimensional Photonic Crystals In The Optical Regime , Jae-Hwang Lee

#### Soft-Lithographical Fabrication Of Three-Dimensional Photonic Crystals In The Optical Regime , Jae-Hwang Lee

*Retrospective Theses and Dissertations*

This dissertation describes several projects to realize low-cost and high-quality three-dimensional (3D) microfabrication using non-photolithographic techniques for layer-by-layer photonic crystals. Low-cost, efficient 3D microfabrication is a demanding technique not only for 3D photonic crystals but also for all other scientific areas, since it may create new functionalities beyond the limit of planar structures. We have developed an advanced microtransfer molding technique, called two-polymer microtransfer molding (2P-[mu]TM) that shows an extremely high yield in layer-by-layer microfabrication sufficient to produce highly layered microstructures. The use of two different photo-curable prepolymers, a filler and an adhesive, allows for fabrication of layered ...