Buffer influence on magnetic dead layer, critical current and thermal stability in magnetic tunnel junctions with perpendicular magnetic anisotropy

We present a thorough research on Ta/Ru-based buffers and their influence on features crucial from the point of view of applications of MTJs, such as critical switching current and thermal stability. We investigate devices consisting of buffer/FeCoB/MgO/FeCoB/Ta/Ru multilayers for three different buffers: Ta 5 / Ru 10 / Ta 3, Ta 5 / Ru 10 / Ta 10 and Ta 5 / Ru 20 / Ta 5 (all thicknesses in nm). In addition, we study systems with a single FeCoB layer deposited above as well as below the MgO barrier. The crystallographic texture and the roughness of the buffers are determined by means of XRD and atomic force microscopy measurements. Furthermore, we examine the magnetic domain pattern, the magnetic dead layer thickness and the perpendicular magnetic anisotropy fields for each sample. Finally, we investigate the effect of the current induced magnetization switching for nanopillar junctions with lateral dimensions ranging from 1 {\mu}m down to 140 nm. Buffer Ta 5 / Ru 10 / Ta 3, which has the thickest dead layer, exhibits a large increase in the thermal stability factor while featuring a slightly lower critical current density value when compared to the buffer with the thinnest dead layer Ta 5 / Ru 20 / Ta 5

Local atomic configuration approach to the nonmonotonic concentration dependence of magnetic properties of Ni(2)Mn(1+x)Z(1-x) (Z = In, Sn, Sb) Heusler alloys

The Ni(2)Mn(1+x)Z(1-x) Heusler alloys, where Z = In, Sn, Sb are attractive candidates for shape memory applications. The effect is directly related to their magnetic properties. We have studied these systems by ab-initio calculations and experiments, focusing on magnetic moments and exchange-bias fields. The calculations indicate that the composition dependence of the total magnetic moment is due to competing ferro-magnetic and antiferromagnetic alignment between Mn atoms on different sublattices and with different local environments. This phenomenon can also explain the composition dependence of the exchange-bias effect. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.Funding Agencies|Polish National Science Centre [DEC-2014/15/B/ST3/02927]; Strategic Research Areas the Swedish eScience Research Centre (SeRC); Advanced Functional Materials at Linkoping University (Faculty Grant SFOMatLiU) [2009 00971]; Ministry of Science and Higher Education of the Russian Federation of NUST "MISIS" [K2-2019-001, 211]</p

Cummulation of coronary artery disease risk factors in arterial hypertension

Wstęp: Nadciśnieniu tętniczemu często towarzyszą inne czynniki ryzyka o charakterze metabolicznym i humoralnym. Powoduje to, że ryzyko związane ze wzrostem ciśnienia tętniczego nie jest ograniczone do zaburzeń hemodynamicznych. Celem naszej pracy było zbadanie rozkładu częstości występowania wybranych czynników ryzyka miażdżycy oraz analiza ilościowa globalnego zagrożenia incydentami wieńcowymi. Metody: Badaniem objęto 926 osób, 751 mężczyzn i 175 kobiet, w wieku 44 &plusmn; 9 lat. U każdego z nich określono poziom glikemii oraz cholesterolu całkowitego, frakcji HDL i trójglicerydów, z których wyliczono poziom cholesterolu frakcji LDL oraz stosunek cholesterolu całkowitego do cholesterolu frakcji HDL. Zmierzono ciśnienie tętnicze, masę ciała, wzrost, obwód talii i bioder, wyliczono wskaźnik masy ciała i stosunek obwodu talii do bioder. Wykonano również standardowe 12-odprowadzeniowe EKG. Za pomocą algorytmu opartego na danych pochodzących z badania Framingham Heart Study obliczono ryzyko incydentu wieńcowego w ciągu następnych 10 lat. Pacjentów podzielono na grupy w zależności od wartości ciśnienia tętniczego według zaleceń ISH. Wyniki: Średnie oszacowane globalne ryzyko incydentu wieńcowego w ciągu następnych 10 lat wynosiło 6,8% w grupie z prawidłowym ciśnieniem tętniczym, 11,9% w grupie z nadciśnieniem łagodnym i 17,1% w grupie z nadciśnieniem ciężkim (p < 0,01). Wnioski: Wyniki naszego badania wskazują na możliwość istotnej redukcji ryzyka choroby niedokrwiennej serca, szczególnie u osób chorych na nadciśnienie tętnicze.Background There are many metabolic and humoral risk factors that coexist with arterial hypertension. Therefore the cardiovascular risk due to the elevated blood pressure is not limited only to the haemodynamic disturbances. The aim of our study was to estimate the distribution of the atherosclerosis risk factors distribution and the global risk of coronary events according to the blood pressure level. Methods The study group consisted of 926 persons (751 men and 175 women), mean age 44 &plusmn; 9 years. We have measured in the serum glucose, total cholesterol, HDL cholesterol and triglycerides levels and calculated the LDL cholesterol level and the total cholesterol to HDL cholesterol ratio. The arterial blood pressure, weight, height, waist and hip circumference were also measured. We have calculated the body mass index and the waist-hip ratio. In each case the 12 lead ecg was performed. The risk of coronary events was calculated by means of Coronary Risk Assessor using the data base from the Framingham Heart Study. The population was divided into blood pressure groups according to ISH recommendations. Results The mean global risk of coronary event during the next 10 years was 6.8% in the normotensive group, 11.9% in the mild hypertension and 17.1% in the moderate and severe hypertension group (p < 0.01). Conclusions There is a considerable possibility of the coronary event risk reduction in the examined population, particularly in the hypertensive patients

Reprogrammability and Scalability of Magnonic Fibonacci Quasicrystals

Magnonic quasicrystals can be used to manipulate spin waves, offering possibilities beyond those of periodic magnonic crystals. The authors investigate one-dimensional magnonic Fibonacci quasicrystals and demonstrate the existence of collective spin waves over a broad range of wave vectors. The spin-wave spectra here are tunable by changing magnetic field amplitude (for continuous band-structure adjustment), magnetization configuration (for reprogrammability), or the dimensions of the elements (for scalability). Beyond being fundamentally interesting, these properties show that magnonic quasicrystals are promising for tomorrow's spintronic, microwave, and magnonic technologies