Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 20 for “"ordering temperature"”.
-
The role of copper on stress evolution and chemical ordering in iron-copper-platinum thin films
The chemical ordering of FePt requires an annealing temperature >500 °C. At these temperatures, grain growth attributed to thermal annealing lowers the areal density in computer hard drives. Multiple paths have been proposed to lower the ordering temperature in order to decrease the grain growth. …
-
Raman Scattering Studies of the Orbital, Magnetic, and Conducting Phases in Double Layer Ruthenates
… This addition of La also lowers the orbital ordering temperature to T ∼ 43 K, and provides a greater sensitivity of the orbital phases to applied magnetic fields, as evidenced by changes in the phases occurring at lower fields and over a greater field range than seen in the undoped system.
-
Explaining a Low-Temperature Magnetic Order in Annealed van der Waals Semiconductor CrSBr
… magnetic material due to its high ferromagnetic ordering temperature (135 K), near-infrared direct bandgap (1.5 eV), and stability in air. In this thesis we report on the detection of a low-temperature magnetic order in annealed CrSBr bulk single crystals using SQUID magnetometry. The order …
-
Correlation of Structure and Magnetic Properties in Charge-Transfer Salt Molecular Magnets Composed of Decamethylmetallocene Electron Donors and Organic Electron Acceptors
… properties of the homologous series including ordering temperature/bulkiness of the alkyl group and intrastack distances/theta values. Correlation of magnetic and structural properties may give some insight into "through-space" magnetic coupling, of which little is understood.
-
Investigation into hardness changes of Pd 11.1 at.% Cu and Pd 11.1 at .% Nb after heat treatments
… systematic heat treatments was used to promote ordering, hardness tests were used to detect changes in the microstructure, which might result from ordering. The Pd-Cu alloy and Pd-Nb alloy did not exhibit any significant hardness changes when heat treated. Transmission Electron Microscopy (TEM) …
-
Theoretical studies of structural and electronic properties in transition metal oxides
… uniform shear distortion below the Jahn-Teller ordering temperature; the Jahn-Teller ordering temperature is estimated and its variation between NdMnO_3 and LaMnO_3, and the relations between distortions are obtained. A good agreement is found between theoretical results and the experimental …
-
An x-ray study of the structure of K1-xRbxCy
… among the K and Rb metal atoms. Extensive low temperature investigations have not revealed any tendency of the mixed layer to either super-order or phase separate. The stacking sequence is independent of alloy composition and is identical to the stacking sequence in KC8 as well as in RbC8. The …
-
Time resolved dynamics of charge density waves in solids : an uncorrelated and a correlated case
… response of La₁.₈₇₅Ba₀.₁₂₅CuO₄ below its charge ordering temperature. Using Landau-Ginsburg free energy analysis, we show that the structural origin of these oscillations can explain the temperature independence of the oscillation frequency. Our experimental observations offer an insight into the …
-
Synthesis and Characterization of Molecule-Based Magnets Containing Methyl-Substituted Phenyltricyanoethylene Acceptors
… magnetic coordination polymers that exhibit ordering temperatures ranging from 160 K to 250 K and display anhysteretic behavior at all temperatures. The magnets synthesized in this project were all characterized and studied using magnetic measurements, infrared spectroscopy, and elemental …
-
Molecular-based magnets constructed from cyanometalate building blocks
… of molecular-based magnets with high magnetic ordering temperatures: they can be easily prepared from well-characterized cyanometalate building blocks, the metal centers are linked covalently into a 3D network, and a wide range of metals with different spin states and oxidation states can be …
-
An Investigation of the Structural and Magnetic Transitions in Ni-Fe-Ga Ferromagnetic Shape Memory Alloys
… alloy was subsequently annealed at various temperatures below and above the B2/L21 ordering temperature. Calorimetry and magnetometry were employed to measure the martensite transformation temperatures and Curie temperatures. Compositional variations of only a few atomic percent result in …
-
Magnetic properties of the rare earth systems neodymium/yttrium and dysprosium/yttrium
… site layers (90$\sp\circ$/at. layer) in the low-temperature limit. The ordering temperature of the helimagnetic phase is $\sim$30 K, an enhancement of about 50% over the bulk T$\rm \sb{N}$ of 19.9 K. As the Nd films or superlattice interlayers become thicker, the magnetic moments of the sample …
-
Synthesis and magnetic properties of novel Ln[subscript 2-x]MxCuO[subscript 4+y] compositions (Ln = La,Pr,Nd,Sm,Eu,Gd; M = Ca,Sr,Ba; 0<=x<=0.2; -0.5<=y<=0.5)
… Ca, Sr; x = 0.05, 0.15), synthesized by the low temperature route, also contain excess oxygen and show different physical properties. [superscript]139La NQR measurements of nonsuperconducting La[subscript]1.85Sr[subscript]0.15CuO[subscript]4.04 show metallic properties. The tolerance factor, …
-
Investigation of the magnetic and magnetocaloric properties of complex lanthanide oxides
… promising magnetic refrigerants for cooling to temperatures currently accessible using non-renewable liquid He. The thesis presents a two-part study of the magnetic and magnetocaloric properties of the geometrically frustrated lanthanide garnets, where the magnetic $Ln^{3+}$ form corner-sharing …
-
Manipulating superconductivity in cuprates with selective ultrafast excitation
… can be generated up to 65 K, near the charge ordering temperature. Two key observations are extracted from the relaxation dynamics. First, the plasma mode relaxes through a collapse of the carrier coherence length and not the carrier density, consistent with a Josephson plasmon.Second, the …
-
Anilate-based Functional Molecular Materials with Conducting and Magnetic Properties
… correlation observed between the ordering temperature values and the electron density on the ligand ring, associated with the electron withdrawing properties of the X substituents, is particularly highlighted. Chapter 4 reports on the structural diversity and the physical …
-
Modelling of Microstructure Development in Silicon-containing Bainitic Free-machining Steels
… bainitic microstructures. The transition temperature from upper to lower bainite is modelled in chapter 7. The model compares the time required for decarburising a supersaturated bainitic ferrite platelet and that for cementite precipitation within the ferrite platelet. Manganese, silicon …
-
Structural and magnetic characterization of Nd-based Nd-Fe and Nd-Fe-Co-Al metastable alloys
… curves the hard magnetic Nd80Fe20 measured at temperatures above 30 K are typical of a hard magnetic material. The coercivity increases from 0.48 to 4.4 T with the temperature decreasing from 300 to 55 K. The demagnetization curves change from single to two-phase type when the temperature …
-
Complex phase behavior of exotic oxides: optical spectroscopy studies
… are localized as small polarons in the high temperature paramagnetic phase, which contribute to the 'collision-limited' diffusive electronic Raman scattering response. The metal-insulator transition is characterized by a change in the low energy electronic Raman scattering response from the …
-
Electrical resistivity of YbRh2Si2 and EuT2Ge2 (T = Co, Cu) at extreme conditions of pressure and temperature
… address the effect that pressure, p, and temperature, T, have on 4f-states of the rare-earth elements in the isostructural YbRh2Si2, EuCo2Ge2, and EuCu2Ge2 compounds. Upon applying pressure, the volume of the unit cell reduces, enforcing either the enhancement of the hybridization of the …