Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Broken-symmetry phases of matter and their effects on electronic and magnetic properties(Montana State University - Bozeman, College of Letters & Science, 2023) Peterson, Sean Fahlman; Chairperson, Graduate Committee: Yves U. Idzerda; This is a manuscript style paper that includes co-authored chapters.Physical symmetries inherent to a material are often reflected in its electronic and magnetic properties. The in-plane four-fold rotational symmetry of thin-film ferromagnets inherent to their tetragonal lattice is also exhibited by their cubic anisotropy. The magnetization as a function of applied magnetic field can be calculated via the Stoner- Wohlfarth model. These calculated hysteresis loops were fit to measured hysteresis loops to determine anisotropy constants consistent with known values. An electronic nematic state reduces the in-plane four-fold rotational symmetry of materials by inducing a structural transition from tetragonal to orthorhombic/monoclinic, with two-fold symmetry. This reduced symmetry persists in the electronic thermal transport. Nematicity enhances nearest-neighbor hopping along one axis and reduces it along the other. This results in a deformed Fermi surface compressed (elongated) along the axis of stronger (weaker) electron hopping. This drags van Hove singularities through the Fermi level, affecting quasiparticle lifetimes. Calculating conductivity from the Boltzmann kinetic equation, nematicity enhances thermal transport along one axis and diminishes it along the other. Additionally, s-wave superconductivity coexisting with nematicity creates a feedback on the superconducting gap with a d-wave instability, which can lead to gapless excitations. In the case of weak feedback, nematic superconductors behave like fully-gapped superconductors along both axes, where transport decreases exponentially with temperature. Once gapless excitations form, transport along both axes becomes T -linear at low-T . Similarly, striped antiferromagnetism (AFM2 and AFM3) reduces the rotational symmetry of a square unit cell to a larger two-fold symmetric magnetic cell. Modeling the band structure with a tight- binding model and considering a smaller periodicity in momentum-space, gaps the Fermi surface along one axis. Calculating conductivity reveals diminished transport along one axis and enhanced thermal transport along the other. Considering d-wave superconductivity in this model results in two cases. One has highly anisotropic transport with greatly enhanced T -linear transport along one axis and diminished transport decreasing exponentially with temperature along the other. The second has weakly anisotropic transport with diminished T -linear conductivity along both axes. The symmetry of a material's properties, such as magnetic anisotropy and thermal transport, are intrinsically linked to their crystalline, electronic, and magnetic symmetries.Item Effect of aryldimethylphosphine electronics on rate of oxidative addition of aryl electrophiles at Ni 0(Montana State University - Bozeman, College of Letters & Science, 2019) Giroux, Michael James; Chairperson, Graduate Committee: Sharon NeufeldtAn analysis of kinetics related to the selectivity of aryldimethylphosphine-nickel complexes for reaction at carbon--chlorine versus carbon--tosylate bonds is reported. A series of aryldimethylphosphine ligands bearing electronically-varied substituents were investigated. The rate constants for oxidative addition of ligand-nickel complexes to either aryl chloride or aryl tosylate substrates were calculated. These rate constants were used to construct Hammett plots describing the susceptibility of oxidative addition at both types of electrophiles to electronic influence from the ligand. Oxidation of catalyst to aryl tosylates yields a plot with a negative slope, while addition to aryl chlorides produces a positive slope. With this, we see that electron donating groups accelerate the addition of catalyst to aryl tosylates, while electron withdrawing groups may change the rate determining step of addition to aryl chlorides.Item The effects on student academic achievement and student self-confidence of a course-specific textbook written for applied electronics math 2(Montana State University - Bozeman, Graduate School, 2016) Phillips, JoAnne Gilbert; Chairperson, Graduate Committee: Peggy Taylor.This research project was developed from the need for a good, affordable textbook for Applied Electronics Math 2 at Madison Area Technical College. When no suitable textbook was found, I chose to write a one specifically designed for that course. This study was motivated by two major research questions in relation to that text: (1) what is the effect on student achievement of using this text? (2) Does the additional emphasis on basic concepts enhance student self-confidence in field-related applications? Data for this project was collected over a period of three semesters. This included not only student grades for homework, quizzes, and exams but information on students' self-confidence levels with respect to mathematics in math and related electronics classes collected at the beginning and end of each semester. Student opinions of the textbook were collected and evaluated using surveys and interviews. Academic scores of the three test classes as compared to a baseline of previous classes taught without a textbook showed expected improvement. However, the greatest improvement was in the self-confidence levels of a majority of the students. Math anxiety was greatly reduced and students declared themselves more prepared to take on the mathematics in their other electronics classes. Student comments about the textbook itself were very favorable. The findings from this research suggest that an affordable book written for a particular course can have a positive effect on both students' academic success in that course and their self-confidence in related areas.Item The use of patterns and pattern-making objects in painting(Montana State University - Bozeman, College of Arts & Architecture, 1982) Svehla, Rudolf; Chairperson, Graduate Committee: Francis J. Noel IIIThe object of my work is a combination of intellectual and emotional activity. With the intellectual part, I work with the most simplified Euclidian spatial format of grid character which, in my opinion, has carried man's scientific and investigative quest from Egyptian architectural accomplishments through the rest of history to the complexity of today's technology. The intellectual activity could be defined in some specific ideas; however, the emotional part of my art deals with intuitive color selection and construction of my particular forms from established symbolism. Pressing these issues into the grid form becomes a mysterious alchemy of my reaction to given information that I absorb from other informative media and through my personal experiences. The series of paintings in my thesis show is based on my research into the variety of patterns and pattern-making objects. These patterns are complex electronic communication equipment schemata interwoven with patterns underlying knitting, crocheting, or weaving. The colors are selected according to the theme of a painting and composed in a somewhat rational order of an established color theory. To a certain extent, I am trying to invent my own personal forms to show how I perceive the world around me. I am fascinated with the power of communication produced by radio and television which influence's the activities of our world in a positive or negative way. This seems to be a reason why I call these paintings 'Radio Series' and try to make them as complex and mysterious as the electronics and their influence that they have on our lives.