Due to the high rate of optical losses and the extensive usage of noble metals, alternative plasmonic materials with maximum tunability and low loss are desired for future plasmonic and metamaterial devices and applications. Herein, the potential of aluminum‐doped zinc oxide (AZO), one of the most prominent members of the transparent conducting oxide family, is demonstrated, for its applicability in plasmonic metamaterials. Using first‐principles density functional theory, combined with optical calculations, AZO‐based, plasmonic split‐ring resonators (SRRs) as model examples are showcased. The results match with experimental reports for the optical dielectric functions of pure and 2.08% Al‐doped zinc oxide (ZnO), if the Hubbard model to the local density approximation is applied. The broadband optical dispersion data for varying dopant concentrations (0%, 2.08%, and 6.25%) are extracted and provided. The subsequent optical response analyses show the existence of pronounced plasmons and inductor–capacitor modes in Al‐doped ZnO SRRs and an enhancement in metallic characteristics and plasmonic performance of AZO upon increasing Al concentration. The findings predict AZO as a low‐loss plasmonic material with promising capability for enhancing future optoelectronics applications. The method introduces a new, versatile approach to design future optical materials of arbitrary geometry.
Molecular Doping (MD) involves the deposition of molecules, containing the dopant atoms and dissolved in liquid solutions, over the surface of a semiconductor before the drive-in step. The control on the characteristics of the final doped samples resides on the in-depth study of the molecule behaviour once deposited. It is already known that the molecules form a self-assembled monolayer over the surface of the sample, but little is known about the role and behaviour of possible multiple layers that could be deposited on it after extended deposition times. In this work, we investigate the molecular surface coverage over time of diethyl-propyl phosphonate on silicon, by employing high-resolution morphological and electrical characterization, and examine the effects of the post-deposition surface treatments on it. We present these data together with density functional theory simulations of the molecules–substrate system and electrical measurements of the doped samples. The results allow us to recognise a difference in the bonding types involved in the formation of the molecular layers and how these influence the final doping profile of the samples. This will improve the control on the electrical properties of MD-based devices, allowing for a finer tuning of their performance.
In this paper, a new half-metallic (HM) double perovskite compound is predicted with the simultaneous presence of ferromagnetism and polar distortion. The structural, electronic and magnetic properties of Sr2MnVO6 (SMVO) are calculated by density functional theory (DFT) with both generalized gradient approximation (GGA) and GGA + U approaches, where U is the on-site Coulomb interaction parameter. Different orderings of B (B′) cationic sites in A2BB′O6 double perovskite structure are evaluated, including rocksalt, columnar and layered arrangements for cubic, monoclinic and tetragonal crystal structures. It is found that the most stable ordering is obtained when B and B′ are placed in a layered type ordering for a tetragonal crystal structure with I4/m space group, which is confirmed by phonon calculations. The B-site ordering of the Mn3+ and V5+ ions in a layered configuration leads to ferromagnetically coupled magnetic moments of 4.17 µB at Mn site and 0.23 µB at V site. Finally, SMVO is found to be a half-metallic ferromagnetic (HM-FM) compound with a band gap of 0.65 eV in a spin down channel with off-centered displacement of V atoms in the octahedral cage (second order Jahn -Teller effect) which can cause ferroelectricity. Therefore, SMVO is predicted to be a polar HM material and a promising candidate for multiferroic property with potential application in spintronics.
The concurrence of half-metallicity and polar nature in Ca2MnVO6 and Ba2MnVO6 double perovskites making them suitable candidates for spintronic device applications.
Subcutaneous nipple sparing mastectomies (NSM) are an important tool in modern oncoplastic surgery. Especially when an immediate implant‐based reconstruction (IBR) is desired, clean margins are of the utmost importance. Central nipple biopsies during surgery serve two main purposes. Most importantly, it is hypothesized that intraoperative pathological evaluation of this biopsy may increase clean margin resection rates. In addition, a general recurrence risk reduction may occur due to the elimination of glandular and ductal components within the nipple. This analysis is a single center, multi‐surgeon, retrospective, head to head analysis. Starting in March 2015, intraoperative central nipple biopsy in NSMs with IBR was introduced at the Municipal Breast Cancer Centre Cologne, Holweide, Germany. This trial retrospectively evaluates global complication rates, clean margin status and local recurrence rates for cohort 1 (NSM/no nipple biopsy, n = 103) vs. cohort 2 (NSM with nipple biopsy, n = 108) Median follow‐up was 15 months. All implant‐based reconstruction procedures used an epipectoral implant pocket. Cohorts were comparable. Global complication rates slightly favored the nipple biopsy cohort with respects to implant loss rate. An involved central nipple biopsy was found in 4.6% (n = 5/108) of the performed NSM procedures leading to the immediate removal of the nipple areola complex. All positive retro‐areolar biopsies correlated with a positive nipple biopsy. However, in n = 1 case we found DCIS discontinual proliferation with an involved nipple biopsy, without a correlating positive retro‐areolar biopsy (ie, 1 false‐negative case was prevented). For the 15 month follow‐up, there was no case of local recurrence within nipple areola complex for both cohorts. With this retrospective head to head analysis of 211 patients, it was shown that the central nipple biopsy correlates well with the retro‐areolar biopsy. There may be a reduction in false negative rates. The procedure is safe to use and should be offered to NSM patients.
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