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In the course of searching for promising topological materials for applications in future topological electronics, we evaluated spin-orbit torques (SOTs) in high-quality sputtered ${\delta}-$TaN/Co20Fe60B20 devices through spin-torque ferromagnetic resonance ST-FMR and spin pumping measurements. From the ST-FMR characterization we observed a significant linewidth modulation in the magnetic Co20Fe60B20 layer attributed to the charge-to-spin conversion generated from the ${\delta}-$TaN layer. Remarkably, the spin-torque efficiency determined from ST-FMR and spin pumping measurements is as large as ${\Theta} =$ 0.034 and 0.031, respectively. These values are over two times larger than for ${\alpha}-$Ta, but almost five times lower than for ${\beta}-$Ta, which can be attributed to the low room temperature electrical resistivity $\sim 74{\mu}{\Omega}$ cm in ${\delta}-$TaN. A large spin diffusion length of at least $\sim8$ nm is estimated, which is comparable to the spin diffusion length in pure Ta. Comprehensive experimental analysis, together with density functional theory calculations, indicates that the origin of the pronounced SOT effect in ${\delta}-$TaN can be mostly related to a significant contribution from the Berry curvature associated with the presence of a topically nontrivial electronic band structure in the vicinity of the Fermi level (EF). Through additional detailed theoretical analysis, we also found that an isostructural allotrope of the superconducting ${\delta}-$TaN phase, the simple hexagonal structure, ${\theta}-$TaN, has larger Berry curvature, and that, together with expected reasonable charge conductivity, it can also be a promising candidate for exploring a generation of spin-orbit torque magnetic random access memory as cheap, temperature stable, and highly efficient spin current sources., Comment: 28 pages, 7 figures

One-lung ventilation (OLV) can be accomplished utilizing a double-lumen tube (DLT) and an endobronchial blocker (EBB) or intentionally placing a standard endotracheal tube (ETT) into a mainstem bronchus. However, secondary options must be available should the primary method fail. We present a case where an EBB and a fiberoptic bronchoscope (FOB) were successfully passed through a left-sided DLT to reestablish right-lung isolation after the DLT bronchial cuff was surgically damaged. We advocate competency in placing both DLTs and EBBs, as well as having EBBs readily accessible as a secondary isolation method during OLV.

Unidirectional spin Hall magnetoresistance (USMR) is a magnetoresistance effect with potential applications to read two-terminal spin–orbit-torque (SOT) devices directly. In this work, we observed a large USMR value (up to 0.7 × 10−11 per A/cm2, 50% larger than reported values from heavy metals) in sputtered amorphous PtSn4/CoFeB bilayers. Ta/CoFeB bilayers with interfacial MgO insertion layers are deposited as control samples. The control experiments show that increasing the interfacial resistance can increase the USMR value, which is the case in PtSn4/CoFeB bilayers. The observation of a large USMR value in an amorphous spin–orbit-torque material has provided an alternative pathway for USMR application in two-terminal SOT devices.

Recent advancement in the switching of perpendicular magnetic tunnel junctions with an electric field has been a milestone for realizing ultra-low energy memory and computing devices. To integrate with current spin-transfer torque-magnetic tunnel junction and spin–orbit torque-magnetic tunnel junction devices, the typical linear fJ/V m range voltage controlled magnetic anisotropy (VCMA) needs to be significantly enhanced with approaches that include new materials or stack engineering. A possible bidirectional and 1.1 pJ/V m VCMA effect has been predicted by using heavily electron-depleted Fe/MgO interfaces. To improve upon existing VCMA technology, we have proposed inserting high work function materials underneath the magnetic layer. This will deplete electrons from the magnetic layer biasing the gating window into the electron-depleted regime, where the pJ/V m and bidirectional VCMA effect was predicted. We have demonstrated tunable control of the Ta/Pd(x)/Ta underlayer's work function. By varying the Pd thickness (x) from 0 to 10 nm, we have observed a tunable change in the Ta layer's work function from 4.32 to 4.90 eV. To investigate the extent of the electron depletion as a function of the Pd thickness in the underlayer, we have performed DFT calculations on supercells of Ta/Pd(x)/Ta/CoFe/MgO, which demonstrate that electron depletion will not be fully screened at the CoFe/MgO interface. Gated pillar devices with Hall cross geometries were fabricated and tested to extract the anisotropy change as a function of applied gate voltage for samples with various Pd thicknesses. The electron-depleted Pd samples show three to six times VCMA improvement compared to the electron accumulated Ta control sample.

Sudden rises of pressure are a common hazard in cryogenic systems. This chapter describes such hazards and the methods by which they may be avoided. Pressure sources, the design of pressure relief systems, the proper calculation of relief valve and vent sizes and descriptions of relief valves are all covered. The impact of pressure safety issues on cryogenic system design is discussed. Example calculations, relevant data and references to pressure vessel codes are included.

This chapter presents a brief summary of the text and lists a final set of general cryogenic safety guidelines.

Oxygen Deficiency Hazards (ODH) are ubiquitous in cryogenic systems. Such hazards can be both insidious and potentially fatal. This chapter describes the nature of the hazard including the physiological effects of oxygen depletion and the mitigations taken to reduce the hazard to acceptable levels. A detailed discussion of how to conduct an ODH Risk Analysis and apply mitigations is presented. The proper response to ODH incidents is discussed along with examples of recent studies, both numerical and experimental, of helium venting scenarios. A list of best practices is included. The chapter appendix contains equipment and human factor failure rates to assist in risk analysis along with a complete example ODH risk analysis.

A significant application of cryogenic technology is found in the cooling of superconducting magnets and superconducting radiofrequency cavities used in particle accelerators. This chapter describes the safety challenges found in such laboratories and the use of written policies, training, hazard analysis, reviews and lessons learned in creating a safe work environment in such facilities. A list of best practices is included.

This chapter discusses aspects of cryogenic safety present in all cryogenic installations. Included are: the effects of cryogenic temperatures and the use of personal protective equipment to protect the body and eyes; first aid procedures for cryogenic burns; safe handling of dewars and cryostats; and hazards associated with system pressure and the presence of magnetic fields. A primary way to avoid accidents in cryogenic facilities is through the use of job hazard analysis and the development of a safe work culture. These topics are also covered. A list of best practices is included. It’s important to note that this chapter is not a complete discussion of cryogenic safety issues. In particular Oxygen Deficiency Hazards (Chap. 4) and details of pressure relief systems (Chap. 3) are not covered here.

The use of liquefied natural gas (LNG) to move natural gas efficiently from producer to consumer is a major industry. This chapter discusses the hazards associated with LNG. The properties of LNG are covered and unique hazards such as stratification and rollover are discussed. More common hazards such as flammability, pressure rise and oxygen deficiency are described. The phenomenon of rapid phase transition is also covered. Reference to existing codes and standards is emphasized. A list of best practices is included.

Understanding the properties of cryogenic fluids and the cryogenic properties of materials is vital to the safe operation of cryogenic systems. This chapter describes the properties of typical fluids used in cryogenics including helium, nitrogen, oxygen and hydrogen as they relate to safety. Lists of suitable and unsuitable materials for cryogenic systems are given and material properties most linked to safety are discussed. Unique safety issues such as the impact of ionizing radiation on liquid nitrogen and the flammability hazards associated with charcoal adsorbers are also covered. References to sources of material properties are given. A list of best practices is included. Additional specific properties are provided in Chap. 5 (Oxygen Systems), Chap. 6 (Hydrogen Systems) and Chap. 7 (LNG).