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Antiferromagnets are of potential use in the development of spintronic devices due to their ultrafast dynamics, insensitivity to external magnetic fields and absence of magnetic stray fields. Similar to their ferromagnetic counterparts, antiferromagnets can store information in the orientations of the collective magnetic order vector. However, the readout magnetoresistivity signals in simple antiferromagnetic films are weak, and reorientation of the magnetic order vector via optical excitation has not yet been achieved. Here we report the reversible and reproducible quenching of antiferromagnetic CuMnAs into nano-fragmented domain states using either electrical or ultrashort optical pulses. The changes in the resistivity of the system approach 20% at room temperature, which is comparable to the giant magnetoresistance ratios in ferromagnetic multilayers. We also obtain a signal readout by optical reflectivity.

Antiferromagnets offer spintronic device characteristics unparalleled in ferromagnets owing to their lack of stray fields, THz spin dynamics, and rich materials landscape. Microscopic imaging of antiferromagnetic domains is one of the key prerequisites for understanding physical principles of the device operation. However, adapting common magnetometry techniques to the dipolar-field-free antiferromagnets has been a major challenge. Here we demonstrate in a collinear antiferromagnet a thermoelectric detection method by combining the magneto-Seebeck effect with local heat gradients generated by scanning far-field or near-field techniques. In a 20-nm epilayer of uniaxial CuMnAs we observe reversible 180∘ switching of the Néel vector via domain wall displacement, controlled by the polarity of the current pulses. We also image polarity-dependent 90∘ switching of the Néel vector in a thicker biaxial film, and domain shattering induced at higher pulse amplitudes. The antiferromagnetic domain maps obtained by our laboratory technique are compared to measurements by the established synchrotron-based technique of x-ray photoemission electron microscopy using x-ray magnetic linear dichroism.

We present a theoretical account of the origin of the shapes of utility, probability weighting, and temporal discounting functions. In an experimental test of the theory, we systematically change the shape of revealed utility, weighting, and discounting functions by manipulating the distribution of monies, probabilities, and delays in the choices used to elicit them. The data demonstrate that there is no stable mapping between attribute values and their subjective equivalents. Expected and discounted utility theories, and also their descendants such as prospect theory and hyperbolic discounting theory, simply assert stable mappings to describe choice data and offer no account of the instability we find. We explain where the shape of the mapping comes from and, in describing the mechanism by which people choose, explain why the shape depends on the distribution of gains, losses, risks, and delays in the environment.

Equilibrium is a state of maximal entropy or disorder; it looks boring. In contrast, systems maintained far from equilibrium exhibit a diversity of fascinating behaviour including pattern formation and turbulence. These systems still pose fundamental questions. In this thesis we report on a study of a granular, far-from-equilibrium system consisting of macroscopic, spherical particles conned in a narrow, cuboidal cell with a square base and large aspect ratio. The cell is vibrated sinusoidally in the direction perpendicular to the long sides. In previous work the system has been shown to behave as a two-dimensional granular gas. If the number of particles in the box exceeds a certain threshold, then we can observe several patterned states upon varying the driving amplitude. The patterns are found to consist of subharmonic standing waves reminiscent of Faraday waves in molecular uids. We observe time-independent patterns as well as a spatiotemporally chaotic state in which the pattern changes its shape rapidly. At higher driving amplitudes impressive wave fronts sweep across the system and destroy the patterns. The waves are replaced by a large-scale circulation if the amplitude is increased further. These states show characteristics of turbulence. We ascertain that the system has no characteristic length-scale after descending into the turbulent state.

The notion of technology-induced disruptive change has generally been applied within academia to teaching and learning. Less explored is the disruption that occurs to research as mainstream technology develops. This article examines the effects of technological change on research in psychology, in particular focussing on the development of web-based empirical research procedures over the past 15 years or so. I discuss the history, challenges and potential of these developments, and put forward some qualified suggestions for some of the future directions that technology will allow research in psychology to take.

Recent interest in university teaching has focused on interactivity in lectures and practical classes, and teachers in several fields have set up systems in which students can interact with the lecturer using mobile-phone based SMS text messaging. This approach has particular potential in psychology, where students could use SMS messaging as a way of responding in simple psychology experiments or demonstrations. We describe a simple architecture for an SMS-based responding, using an SMS-to-HTTP message relay service, and a php/mySQL input-output handler. We describe briefly two experiments we have run using the system. The first experiment examined anchoring effects in an SMS-based auction. The second experiment examined delay discounting, with participants indicating their intertemporal preferences using SMS. Finally, we evaluate the feedback we obtained from students, about the practical and conceptual issues surrounding text-message based responding.

There has been discussion over the extent to which delay discounting – as prototypically shown by a preference for a smaller-sooner sum of money over a larger-later sum – measures the same kind of impulsive preferences that drive non-financial behavior. To address this issue a dataset was analyzed, containing 42,863 participants’ responses to a single delay-discounting choice, along with self-report behaviors that can be considered as impulsive. Choice of a smaller-sooner sum was associated with several demographics: younger age, lower income, lower education; and impulsive behaviors: earlier age of first sexual activity and recent relationship infidelity, smoking, and higher body mass index. These findings suggest that at least an aspect of delay discounting preference is associated with a general trait influencing other forms of impulsivity, and therefore that high delay discounting is another form of impulsive behavior.