Templates for magnetic symmetry and altermagnetism in hexagonal MnTe

The symmetry of long-range magnetic order in manganese telluride (alpha-MnTe) is unknown. Likewise, its standing as an altermagnet. To improve the situation, we present symmetry informed Bragg diffraction patterns based on a primary magnetic order parameter for antiferromagnetic alignment between Mn dipoles. It does not break translation symmetry in a centrosymmetric structure, in keeping with an accepted definition of altermagnetism. Our templates serve x-ray diffraction that benefits from signal enhancement using a Mn atomic resonance, and neutron scattering. Even rank multipoles in magnetic neutron diffraction reflect a core requirement of altermagnetism, because they are zero for strong spin-orbit coupling. Symmetry in the templates demands that nuclear and magnetic contributions possess the same phase, which enables standard neutron polarization analysis on Bragg spots with overlapping contributions. However, three of the four templates generate Bragg spots that do not appear in the lattice (nuclear) diffraction pattern, i.e., Bragg spots that are basis-forbidden and purely magnetic in origin. On the other hand, identical symmetry demands a 90 deg phase shift between magnetic (time-odd) and charge-like (time-even, Templeton-Templeton) contributions to x-ray scattering amplitudes. Consequently, circular polarization in the primary beam of x-rays is rotated. The difference in the intensities of a Bragg spot measured with right- and left-handed circular primary polarization defines a chiral signature. Further tests include predictions in three out four templates of zero intensity in a specified channel of x-ray polarization. Diffraction properties of a template are radically different from those of a parity-time (PT)-symmetric antiferromagnet, for its symmetry allows a linear ME effect and prohibits both a PM effect and a chiral signature

The privacy calculus in the context of novel health technology for diagnosing and tracking infectious diseases:The role of disease severity and technology's evidence base for effectiveness in adoption and voluntary health data-sharing

In the past decades, accelerated by the recent COVID pandemic, the field of healthcare has faced technological advancements, such as wearables and mobile applications, that collect personal or health data. However, such tools are ineffective if they are not adopted by a large part of the population or if relevant health data, collected by the application, are not (voluntarily) shared. This study assessed the role of disease severity and evidence base for the effectiveness of the technology in the Privacy Calculus risk-benefit trade-off to contribute or hinder technology acceptance and data sharing. A large-scale 2 × 2 × 2 online vignette experiment (n = 822) was carried out, where participants were presented with a hypothetical scenario describing a novel health technology for diagnosing and tracking of infectious diseases. The results indicated that participants’ privacy concerns negatively affected their intention to use the technology and willingness to share data, and that a high severity of the disease weakened this relationship. None of the other expected effects on intentions to use, willingness to share data or privacy concerns, were significant. These findings highlight the role of privacy as a barrier to technology acceptance, and suggest disease severity plays a role in the Privacy Calculus risk-benefit trade off by weakening the negative effect of privacy concerns on adoption in contexts where disease severity is high.</p

Spin and orbital moments of ultra-thin Fe films on various semiconductor surfaces

The magnetic moments of ultrathin Fe films on three different III-V semiconductor substrates, namely GaAs, InAs and In0.2Ga0.8As have been measured with X-ray magnetic circular dichroism at room temperature to assess their relative merits as combinations suitable for next-generation spintronic devices. The results revealed rather similar spin moments and orbital moments for the three systems, suggesting the relationship between film and semiconductor lattice parameters to be less critical to magnetic moments than magnetic anisotropy

Semiparametric theory and empirical processes in causal inference

In this paper we review important aspects of semiparametric theory and empirical processes that arise in causal inference problems. We begin with a brief introduction to the general problem of causal inference, and go on to discuss estimation and inference for causal effects under semiparametric models, which allow parts of the data-generating process to be unrestricted if they are not of particular interest (i.e., nuisance functions). These models are very useful in causal problems because the outcome process is often complex and difficult to model, and there may only be information available about the treatment process (at best). Semiparametric theory gives a framework for benchmarking efficiency and constructing estimators in such settings. In the second part of the paper we discuss empirical process theory, which provides powerful tools for understanding the asymptotic behavior of semiparametric estimators that depend on flexible nonparametric estimators of nuisance functions. These tools are crucial for incorporating machine learning and other modern methods into causal inference analyses. We conclude by examining related extensions and future directions for work in semiparametric causal inference

High-order Dy multipole motifs observed in DyB2C2 with resonant soft x-ray Bragg diffraction

Resonant soft x-ray Bragg diffraction at the Dy M4,5 edges has been exploited to study Dy multipole motifs in DyB2C2. Our results are explained introducing the intra-atomic quadrupolar interaction between the core 3d and valence 4f shell. This allows us to determine for the first time higher order multipole moments of dysprosium $4f$ electrons and to draw their precise charge density. The Dy hexadecapole and hexacontatetrapole moment have been estimated at -20% and +30% of the quadrupolar moment, respectively. No evidence for the lock-in of the orbitals at T_N has been observed, in contrast to earlier suggestions. The multipolar interaction and the structural transition cooperate along c but they compete in the basal plane explaining the canted structure along [110].Comment: 4 pages, 3 figure

Strain dependence of the Mn anisotropy in ferromagnetic semiconductors observed by x-ray magnetic circular dichroism

We demonstrate sensitivity of the Mn 3d valence states to strain in the ferromagnetic semiconductors (Ga,Mn)As and (Al,Ga,Mn)As, using x-ray magnetic circular dichroism (XMCD). The spectral shape of the Mn $L_{2,3}$ XMCD is dependent on the orientation of the magnetization, and features with cubic and uniaxial dependence are distinguished. Reversing the strain reverses the sign of the uniaxial anisotropy of the Mn $L_3$ pre-peak which is ascribed to transitions from the Mn 2p core level to p-d hybridized valence band hole states. With increasing carrier localization, the $L_3$ pre-peak intensity increases, indicating an increasing 3d character of the hybridized holes.Comment: 4 pages plus 2 figures, accepted for publication in Physical Review