We studied several aspects of the Mott metal-insulator transition in the disordered case. The model on which we based our analysis is the disordered Hubbard model, which is the simplest model capable of capturing the Mott metal-insulator transition. We investigated this model through statistical dynamical mean-field theory (statDMFT). This theory is a natural extension of dynamical mean-field theory (DMFT), which has been used with relative success in the past several years with the purpose of describing the Mott transition in the clean case. As is the case for the latter theory, statDMFT incorporates the electronic correlation effects only in their local manifestations. Disorder, on the other hand, is treated in such a way as to incorporate Anderson localization effects. With this technique, we analyzed the disordered two-dimensional Mott transition, using the quantum Monte Carlo algorithm to solve the associated single-impurity problems. We found spinodal lines at which the metal and insulator ceased to be metastable. We also studied spatial fluctuations of local quantities, such as self-energy and local Green's function, and showed the appearance of metallic regions within the insulator and vice versa. We carried out an analysis of finite-size effects and showed that, in agreement with the theorems of Imry and Ma [Y. Imry and S. K. Ma, Phys. Rev. Lett. 35, 1399 (1975).], the first-order transition is smeared in the thermodynamic limit. We analyzed transport properties by means of a mapping to a random classical resistor network and calculated both the average current and its distribution across the metal-insulator transition.

Magnetic resonance imaging (MRI) is widely used in diagnostic medicine. MRI uses the static magnetic field to polarize nuclei spins, fast-switching magnetic field gradients to generate temporal and spatial resolution, and radiofrequency (RF) electromagnetic waves to control the spin orientation. All these forms of magnetic static and electromagnetic RF fields interact with human tissue and cells. However, reports on the MRI technique’s effects on the cells and human body are often inconsistent or contradictory. In both research and clinical MRI, recent progress in improving sensitivity and resolution is associated with the increased magnetic field strength of MRI magnets. Additionally, to improve the contrast of the images, the MRI technique often employs contrast agents, such as gadolinium-based Dotarem, with effects on cells and organs that are still disputable and not fully understood. Application of higher magnetic fields requires revisiting previously observed or potentially possible bio-effects. This article focuses on the influence of a static magnetic field gradient with and without a gadolinium-based MRI contrast agent (Dotarem) and the cellular and molecular effects of Dotarem on macrophages.

We discuss charge density wave transport as the periodic flow of a quantum fluid of electron–phonon correlates, viewed as quantum solitons, within the condensate. Pair creation of charged soliton droplets is prevented by their electrostatic energy below a Coulomb-blockade threshold electric field. Above threshold, the quantum fluid flows in drip-like fashion as microscopic entities tunnel coherently from one charging energy macrostate to the next. We summarize the time-correlated soliton tunneling model and compare simulations of coherent oscillations, narrow band noise, and current–voltage characteristics with experiment. We also explore the possibility of collective quantum behavior at room temperature in some materials. Finally, we discuss potential applications in quantum information processing.

We present progress in the use of rf/microwave standing waves in REBCO tapes to develop a nondestructive (NDE) technique for quench detection. REBCO tape can be treated as a transmission line for electromagnetic waves at high frequencies, or alternatively, as a capacitor at low frequencies. In principle, standing waves in a transmission line can be excited either capacitively or inductively, which provides great flexibility and multitude of choices for circuit optimization to form a system that is most sensitive to current and temperature disturbances. EM standing waves in transmission lines are particularly sensitive to any change in uniformity along its length, either in its geometry or in material property changes such as permittivity or of conductivity of the layers. Upon quench initiation, the standing waves formed in the transmission line are immediately disturbed, which can be readily sensed by a network analyzer and in general leads to formation of new peaks, change in Q factor and frequency shifts of existing peaks, and these signal changes will be sensed almost instantaneously. We present simulation and experimental results on short segments of REBCO tape subjected to transport dc current and simultaneously coupled as a transmission line. Heat pulses were applied to the tapes to increase tape's temperature and collect and analyze transmission line fingerprint changes. The results are analyzed and discussed in terms of the magnitude of sensitivity to quench.

The nucleation and dynamics of Josephson and Abrikosov vortices determine the critical currents of layered high-T_c superconducting (HTS) thin films, grain boundaries, and coated conductors, so understanding their mechanisms is of crucial importance. Here, we treat pair creation of Josephson and Abrikosov vortices in layered superconductors as a secondary Josephson effect. Each full vortex is viewed as a composite fluid of micro-vortices, such as pancake vortices, which tunnel coherently via a tunneling matrix element. We introduce a two-terminal magnetic (Weber) blockade effect that blocks tunneling when the applied current is below a threshold value. We simulate vortex tunneling as a dynamic, time-correlated process when the current is above threshold. The model shows nearly precise agreement with voltage-current (V-I) characteristics of HTS cuprate grain boundary junctions, which become more concave rounded as temperature decreases, and also explains the piecewise linear V-I behavior observed in iron-pnictide bicrystal junctions and other HTS devices. When applied to either Abrikosov or Josephson pair creation, the model explains a plateau seen in plots of critical current vs. thickness of HTS-coated conductors. The observed correlation between theory and experiment strongly supports the proposed quantum picture of vortex nucleation and dynamics in layered superconductors.

Many Mott systems feature a first-order metal-insulator transition at finite temperatures, with an associated phase coexistence region displaying inhomogeneities and local phase separation. Here one typically finds “bubbles” or domains of the respective phases, which are separated by surprisingly thick, or fat, domain walls, as revealed both by imaging experiments and recent theoretical modeling. To gain insight into this unexpected behavior, we perform a systematic model study of the structure of such metal-insulator domain walls around the Mott point, within the dynamical mean-field theory framework. Our study reveals that a mechanism producing such “fat” domain walls can be traced to strong magnetic frustration, which is expected to be a robust feature of “spin-liquid” Mott systems.