Influence of strain and polycrystalline ordering on magnetic properties of high moment rare earth metals and alloys

Abstract Despite being the most suitable candidates for solenoid pole pieces in state-of-the-art superconductor-based electromagnets, the intrinsic magnetic properties of heavy rare earth metals and their alloys have gained comparatively little attention. With the potential of integration in micro and nanoscale devices, thin films of Gd, Dy, Tb, DyGd and DyTb were plasma-sputtered and investigated for their in-plane magnetic properties, with an emphasis on magnetization versus temperature profiles. Based on crystal structure analysis of the polycrystalline rare earth films, which consist of a low magnetic moment fcc layer at the seed interface topped with a higher moment hcp layer, an experimental protocol is introduced which allows the direct magnetic analysis of the individual layers. In line with the general trend of heavy lanthanides, the saturation magnetization was found to drop with increasing unit cell size. In situ annealed rare earth films exceeded the saturation magnetization of a high-moment Fe65Co35 reference film in the cryogenic temperature regime, proving their potential for pole piece applications; however as-deposited rare earth films were found completely unsuitable. In agreement with theoretical predictions, sufficiently strained crystal phases of Tb and Dy did not exhibit an incommensurate magnetic order, unlike their single-crystal counterparts which have a helical phase. DyGd and DyTb alloys followed the trends of the elemental rare earth metals in terms of crystal structure and magnetic properties. Inter-rare-earth alloys hence present a desirable blend of saturation magnetization and operating temperature.</jats:p

Optical properties of Au-Hf thin films

The optical properties of thin films of intermetallic Au$_{3}$Hf were experimentally investigated for the first time, which display clear plasmonic properties in the optical and near infrared region with negative permittivity. In contrast to similar alloys, such as films of Au$_{3}$Zr, the films express more negative $\epsilon'$ values and lower $\epsilon''$ values across most of the wavelengths (370-1570 nm) investigated. The Au$_{3}$Hf films were fabricated by DC magnetron sputtering at a range of deposition temperatures, from room temperature to 415$^{o}$C, and annealed at different vacuum levels. The films mostly formed as a combination of Au$_{3}$Hf, Au$_{2}$Hf and Au$_{4}$Hf phases when deposited below 400$^{o}$C, and exclusively Au$_{3}$Hf phase at above 400$^{o}$C, indicating key conditions for isolating this phase. The films were stable when annealed at 10$^{-8}$ Torr, but when annealed again at 10$^{-6}$ Torr the films oxidised and changed into a mix of Au- Hf phases, suggesting resistance to oxidization may be an issue for un-encapsulated applications at elevated temperatures.Comment: 19 pages, including references, plus 3 pages of supplementary material. 8 figures and 1 table in main text, 1 figure and 1 table in supplementary materia

Synthesis of plasmonically active titanium nitride using a metallic alloy buffer layer strategy

Titanium nitride (TiN) has emerged as a highly promising alternative to traditional plasmonic materials. This study focuses on the inclusion of a Cr90Ru10 buffer layer between the substrate and the thin TiN film, which enables the use of cost-effective, amorphous technical substrates while preserving high film quality. We report best-in-class TiN thin films fabricated on fused silica wafers, achieving a maximum plasmonic figure of merit (FOM), -ε′/ε′′ of approximately 2.8, even at a modest wafer temperature of around 300°C. Furthermore, we delve into the characterization of TiN thin film quality and fabricated TiN triangular nanostructures, employing attenuated total reflectance and cathodoluminescence techniques to highlight their potential applications in surface plasmonics

Synthesis of plasmonically active titanium nitride using a metallic alloy buffer layer strategy

Titanium nitride (TiN) has emerged as a highly promising alternative to traditional plasmonic materials. This study focuses on the inclusion of a Cr90Ru10 buffer layer between the substrate and thin TiN film, which enables the use of cost-effective, amorphous technical substrates while preserving high film quality. We report best-in-class TiN thin films fabricated on fused silica wafers, achieving a maximum plasmonic figure of merit, −ϵ′/ϵ″, of approximately 2.8, even at a modest wafer temperature of around 300 °C. Furthermore, we delve into the characterization of TiN thin film quality and fabricated TiN triangular nanostructures, employing attenuated total reflectance and cathodoluminescence techniques to highlight their potential applications in surface plasmonics.<br/

Mitral valve repair for bacterial endocarditis

Twenty-two patients with mitral insufficiency resulting from native valve endocarditis underwent mitral valve repair. Six patients had acute endocarditis with positive blood cultures and active valve infection. Sixteen patients were cured of active infection, but mitral insufficiency developed as a result of prior infection. Mean age was 48.5 ± 21.7 years; 13 (59 %) were male. Mean New York Heart Association functional class was 2.6 ± 1.2. Multiple valve lesions were present in 11 (50%) patients. Valve abnormalities included leaflet perforation in 13 patients, chordal rupture or elongation in 14, vegetations in 5; and annular abscess in 1. In patients with acute endocarditis all macroscopically infected tissue was excised. Multiple techniques were required to achieve valve competence. Suture or patch closure of perforation was done in 14 patients, chordal shortening or transfer in 9, leaflet resection and closure in 4, leaflet resection with pericardial patching in 5, and annuloplasty in 15. Mitral valvuloplasty was combined with other procedures in 11 (50%) patients. There were two (9%) hospital deaths, both occurring in patients with healed endocarditis. There was one (9%) death in a patient undergoing an isolated procedure and one (9%) in a patient undergoing a combined procedure. Mean follow-up was 24 ± 16.8 months and was complete. Seventeen (85%) were in New York Heart Association functional class I, and three (15%) were in class II. There were no late deaths, reoperations, recurrent endocarditis, thromboembolic events, or other valve-related morbidity. We conclude that mitral valve repair for insufficiency resulting from bacterial endocarditis (1) is possible in acute and healed disease, (2) has a low operative mortality, and (3) has resulted in patients free of recurrent infection and valve-related morbidity and mortality. Mitral valve repair is an attractive alternate to valve replacement in bacterial endocarditis. (J Thorac Cardiovasc Surg 1992;103:124—9