Spin Dependent Tunneling in FM|semiconductor|FM structures

Here we show that ordinary band structure codes can be used to understand the mechanisms of coherent spin-injection at interfaces between ferromagnets and semiconductors. This approach allows the screening of different material combinations for properties useful for obtaining high tunneling magnetoresistance (TMR). We used the Vienna Ab-initio Simulation Code (VASP) to calculate the wave function character of each band in periodic epitaxial Fe(100)|GaAs(100) and Fe(100)|ZnSe(100) structures. It is shown that Fe wave functions of different symmetry near Fermi energy decay differently in the GaAs and ZnSe.Comment: Accepted for publication in MMM'05 Proceedings. 7 pages, 5 figure

UTILIZATION OF MIND-BODY PRACTICES FOR ADULTS WITH FIBROMYALGIA: 2017 NATIONAL HEALTH INTERVIEW SURVEY

Fibromyalgia (FM) is a medical condition characterized by chronic pain and tenderness. Individuals with FM may experience burdensome symptoms, which impact their health-related quality of life. Treatment for FM includes pharmacological and non pharmacological practices. Non-pharmacological treatments for FM include dietary management, routine exercise, and physical and mind-body therapies. There is growing evidence that the utilization of mind-body practices is increasing in the United States, but there have been limited investigations done to observe the use of mind-body practices in the FM population. The purpose of this study is to identify predictors of the use of meditation and/or meditative movement in individuals with FM. The secondary aims are to describe the percentage of adults with and without FM that use mind-body practices and compare the demographic traits of people with FM who use meditation versus meditative movement. Using data from the 2017 National Health Interview Survey, descriptive statistics were used to determine the percentage of adults that use mind-body practices between those with FM and those without FM. To compare demographic and medical characteristics of individuals with FM that use meditation, meditative movement, both or neither practices, χ2 tests were performed. Lastly, a multinomial logistic regression model was used to examine predictors of using meditation, meditative movement, neither or both practices. The analyses revealed that people without FM were significantly more likely to use mantra and spiritual meditation, yoga, and tai chi compared to people with FM. Predictors of using mind-body practices include being young, female, and college educated

Electromigration in thin tunnel junctions with ferromagnetic/nonmagnetic: nanoconstrictions, local heating, and direct and wind forces

Current Induced Resistance Switching (CIS) was recently observed in thin tunnel junctions with ferromagnetic (FM) electrodes \emph{i.e} FM/I/FM. This effect was attributed to electromigration of metallic atoms in nanoconstrictions in the insulating barrier (I). Here we study how the CIS effect is influenced by a thin non-magnetic (NM) Ta layer, deposited just below the AlO$_x$ insulating barrier in tunnel junctions of the type FM/NM/I/FM (FM=CoFe). Enhanced resistance switching occurs with increasing maximum applied current (\Imax), until a plateau of constant CIS is reached for \Imax\sim65 mA (CIS$\sim$60%) and above. However, such high electrical currents also lead to a large ($\sim$9%) irreversible resistance decrease, indicating barrier degradation. Anomalous voltage-current characteristics with negative derivative were also observed near \pm\Imax and this effect is here attributed to heating in the tunnel junction. One observes that the current direction for which resistance switches in FM/NM/I/FM (clockwise) is opposite to that of FM/I/FM tunnel junctions (anti-clockwise). This effect will be discussed in terms of a competition between the electromigration contributions due to the so called direct and wind forces. It will be shown that the direct force is likely to dominate electromigration in the Ta (NM) layers, while the wind contribution likely dominates in the CoFe (FM) layers

Obtaining strong ferromagnetism in diluted Gd-doped ZnO thin films through controlled Gd-defect complexes

We demonstrate the fabrication of reproducible long-range ferromagnetism (FM) in highly crystalline Gdx Zn 1−xO thin films by controlling the defects. Films are grown on lattice-matched substrates by pulsed laser deposition at low oxygen pressures (≤25 mTorr) and low Gd concentrations (x ≤ 0.009). These films feature strong FM (10 μB per Gd atom) at room temperature. While films deposited at higher oxygen pressure do not exhibit FM, FM is recovered by post-annealing these films under vacuum. These findings reveal the contribution of oxygen deficiency defects to the long-range FM. We demonstrate the possible FM mechanisms, which are confirmed by density functional theory study, and show that Gd dopants are essential for establishing FM that is induced by intrinsic defects in these films

Superconductivity induced by longitudinal ferromagnetic fluctuations in UCoGe

From detailed angle-resolved NMR and Meissner measurements on a ferromagnetic (FM) superconductor UCoGe (T_Curie ~ 2.5 K and T_SC ~ 0.6 K), we show that superconductivity in UCoGe is tightly coupled with longitudinal FM spin fluctuations along the c axis. We found that magnetic fields along the c axis (H || c) strongly suppress the FM fluctuations and that the superconductivity is observed in the limited magnetic field region where the longitudinal FM spin fluctuations are active. These results combined with model calculations strongly suggest that the longitudinal FM spin fluctuations tuned by H || c induce the unique spin-triplet superconductivity in UCoGe. This is the first clear example that FM fluctuations are intimately related with superconductivity.Comment: 4 pages, 5 figures, to appear in PR