Effect of Defects on the Line shape of Electron Paramagnetic Resonance Signals from the Single-Molecule Magnet Mn12: A Theoretical Study

We herein estimate the effect of lattice defects on the line shape of electron paramagnetic resonance (EPR) signals from a single crystal of the S=10 single-molecule magnet Mn$_{12}$ with the external magnetic field along the crystal c axis. A second-order perturbation treatment of an effective single-spin Hamiltonian indicates that a small, random, static misorientation of the magnetic symmetry axes in a crystalline lattice can lead to asymmetric EPR peaks. Full spectra are simulated by calculating probability-distribution functions for the resonant fields, employing distributions in the tilt angle of the easy axis from the c axis, in the uniaxial anisotropy parameter, and in the $g$-factor. We discuss conditions under which the asymmetry in the EPR spectra becomes prominent. The direction and magnitude of the asymmetry provide information on the specific energy levels involved with the EPR transition, the EPR frequency, and the distribution in the tilt angle.Comment: published versio

Entrapment of magnetic micro-crystals for on-chip electron spin resonance studies

On-chip Electron Spin Resonance (ESR) of magnetic molecules requires the ability to precisely position nanosized samples in antinodes of the electro-magnetic field for maximal magnetic interaction. A method is developed to entrap micro-crystals containing spins in a well defined location on a substrate's surface. Traditional cavity ESR measurements are then performed on a mesoscopic crystal at 34 GHz. Polycrystalline diluted Cr$^{5+}$ spins were entrapped as well and measured while approaching the lower limit of the ESR sensitivity. This method suggests the feasibility of on-chip ESR measurements at dilution refrigerator temperatures by enabling the positioning of samples atop an on-chip superconducting cavity.Comment: to appear in Journal of Applied Physic

Spin-Orbit Coupling Fluctuations as a Mechanism of Spin Decoherence

We discuss a general framework to address spin decoherence resulting from fluctuations in a spin Hamiltonian. We performed a systematic study on spin decoherence in the compound K$_6$[V$_{15}$As$_6$O$_{42}$(D$_2$O)] $\cdot$ 8D$_2$O, using high-field Electron Spin Resonance (ESR). By analyzing the anisotropy of resonance linewidths as a function of orientation, temperature and field, we find that the spin-orbit term is a major decoherence source. The demonstrated mechanism can alter the lifetime of any spin qubit and we discuss how to mitigate it by sample design and field orientation.Comment: submitte

An EPR methodology for measuring the London penetration depth for the ceramic superconductors

The use is discussed of electron paramagnetic resonance (EPR) as a quick and easily accessible method for measuring the London penetration depth, lambda for the high T(sub c) superconductors. The method utilizes the broadening of the EPR signal, due to the emergence of the magnetic flux lattice, of a free radical adsorbed on the surface of the sample. The second moment, of the EPR signal below T(sub c) is fitted to the Brandt equation for a simple triangular lattice. The precision of this method compares quite favorably with those of the more standard methods such as micro sup(+)SR, Neutron scattering, and magnetic susceptibility

Shadow Administrative Constitutionalism and the Creation of Surveillance Culture

Article published in the Michigan State Law Review

The Influence of Coating Adhesives on the Stiffness of Paper

The main purpose of this project was to study the effect coating adhesive has on the stiffness of paper. This work enables one to compare data on what influence adhesive with and without supercalendering has on the stiffness and caliper of the paper. The project was performed with six formulations with a different adhesive or adhesive combination in each. The adhesives were six types, casein, protein, starch, casein + latex, protein + latex and starch + latex. It has been found in general that stiffness of all the paper samples increased when coating adhesive was applied on the surface. The starch gave the higher stiffness followed by protein and casein in that order. By adding the latex to the casein, starch and protein formulations the stiffness decreased in all cases. It was also noted that the stiffness was higher in the machine direction than in the cross direction of the paper. Stiffness and caliper decreased in all cases with supercalendering

Automated data acquisition and reduction system for torsional braid analyzer

Automated Data Acquisition and Reduction System (ADAR) evaluates damping coefficient and relative rigidity by storing four successive peaks of waveform and time period between two successive peaks. Damping coefficient and relative rigidity are then calculated and plotted against temperature or time in real time