Physics Commons^™

Effects Of Disorder And Low Dimensionality On Frozen Dynamics In Ca3co2-Xmnxo6, Brian Wesley Casas

USF Tampa Graduate Theses and Dissertations

Complex oxides represent an intersection of play grounds for the existence of exciting new fundamental physics and materials with potential technological implications. The realization of many exciting properties of these systems rely on the coupling of electronic, structural and magnetic degrees of freedom. Additionally, competing interactions within each type of coupling discussed previously lead to theoretically diverse ground states, which under the application of an external perturbation, can be tuned and probed.

Ca3Co¬2-xMnxO6 represent a quasi-one dimensional Ising spin chain system oriented in an antiferromagnetic triangular lattice. The exotic behavior of the undoped compound Ca3Co2O6 has inspired work on continuing …

Enhanced Magnetism In Dy And Tb At Extreme Pressure, Jinhyuk Lim

Arts & Sciences Electronic Theses and Dissertations

At ambient pressure all lanthanide metals order magnetically at temperatures at or below ambient. The magnetic ordering is known to result from the indirect exchange interaction between localized 4f magnetic moments mediated by the surrounding conduction electrons, the so-called Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. With the RKKY interaction the magnetic ordering temperature To is expected to be proportional to the de Gennes factor which is a function of the Landé g factor gJ and the total angular momentum J. For example, Gd has the highest value of To, 292 K, at ambient pressure as it has the largest de Gennes factor of …

Evolution Of Magnetism In Single-Crystal Ca2Ru1−XIrXO4(0≤X≤0.65), Shujuan Yuan, Jsaminka Terzic, J. C. Wang, L. Li, Saicharan Aswartham, W. H. Song, F. Ye, Gang Cao

Physics and Astronomy Faculty Publications

We report structural, magnetic, transport, and thermal properties of single-crystal Ca₂Ru_1−xIr_xO₄(0≤x≤0.65). Ca₂RuO₄ is a structurally driven Mott insulator with a metal-insulator transition at T_MI=357K, which is well separated from antiferromagnetic order at T_N=110K. Substitution of a 5_d element, Ir, for Ru enhances spin-orbit coupling and locking between the structural distortions and magnetic moment canting. Ir doping intensifies the distortion or rotation of Ru/IrO₆ octahedra and induces weak ferromagnetic behavior along the c axis. In particular, Ir doping suppresses T_N but …

Magnetic Fields, Voltage, And Currents Problems (Practice Questions), Arun Saha

Physics and Astronomy Ancillary Materials

This set of lecture-oriented practice questions was developed under a Round One ALG Textbook Transformation Grant.

Giant Magnetization Canting Due To Symmetry Breaking In Zigzag Co Chains On Ir(001), B. Dupé, Jessica E. Bickel, Y. Mokrousov, F. Otte, Kirsten Von Bergmann, André Kubetzka, Stefan Heinze, Roland Wiesendanger

Physics Faculty Publications

We demonstrate a canted magnetization of biatomic zigzag Co chains grown on the (5 × 1) reconstructed Ir(001) surface using density functional theory (DFT) calculations and spin-polarized scanning tunneling microscopy (SP-STM) experiments. It is observed by STM that biatomic Co chains grow in three different structural configurations. Our DFT calculations show that they are all in a ferromagnetic (FM) state. Two chain types possess high symmetry due to two equivalent atomic strands and an easy magnetization direction that is along one of the principal crystallographic axes. The easy magnetization axis of the zigzag Co chains is canted away from the …

Exchange Mechanisms In Macroscopic Ordered Organic Magnetic Semiconductors, Naveen Rawat

Graduate College Dissertations and Theses

Small molecule organic semiconductors such as phthalocyanines and their derivatives represent a very interesting alternative to inorganic semiconductor materials for the development of flexible electronic devices such as organic thin field effect transistors, organic Light Emitting Diodes and photo-voltaic cells. Phthalocyanine molecules can easily accommodate a variety of metal atoms as well in the central core of the molecule, resulting in wide range of magnetic properties. Exploration of optical properties of organic crystalline semiconductors thin films is challenging due to sub-micron grain sizes and the presence of numerous structural defects, disorder and grain boundaries. However, this can be overcome by …