Magneto-Optical properties in thin film Topological insulators with quadratic momentum term

In this work we investigate the influence of quadratic in momentum term (Schrodinger term) on magneto-transport properties of thin film topological insulators. The Schrodinger term modifies the Dirac cones into an hourglass shape which results in inter and intraband Landau levels crossings. Breaking of the particle-hole symmetry in Landau level spectrum in the presence of k2 term leads to asymmetrical density of states profile. We calculate collisional and Hall conductivity for mixed Dirac-Schrodinger system in linear response regime and show oscillatory behavior in collisional con- ductivity, while Zeeman and hybridization terms provide a doubly split peak structure in collisional conductivity for the case m/me → ∞. We calculate Hall conductivity analytically and show that for mixed system filling factor is not symmetric about Fermi energy unlike symmetic plateaus for pure Dirac case.

Mechanical plasticity of collagen directs branch elongation in human mammary gland organoids

Epithelial branch elongation is a central developmental process during branching morphogenesis in diverse organs. This fundamental growth process into large arborized epithelial networks is accompanied by structural reorganization of the surrounding extracellular matrix (ECM), well beyond its mechanical linear response regime. Here, we report that epithelial ductal elongation within human mammary organoid branches relies on the non-linear and plastic mechanical response of the surrounding collagen. Specifically, we demonstrate that collective back-and-forth motion of cells within the branches generates tension that is strong enough to induce a plastic reorganization of the surrounding collagen network which results in the formation of mechanically stable collagen cages. Such matrix encasing in turn directs further tension generation, branch outgrowth and plastic deformation of the matrix. The identified mechanical tension equilibrium sets a framework to understand how mechanical cues can direct ductal branch elongation.

Geometric Optimisation of Quantum Thermodynamic Processes

Differential geometry offers a powerful framework for optimising and characterising finite-time thermodynamic processes, both classical and quantum. Here, we start by a pedagogical introduction to the notion of thermodynamic length. We review and connect different frameworks where it emerges in the quantum regime: adiabatically driven closed systems, time-dependent Lindblad master equations, and discrete processes. A geometric lower bound on entropy production in finite-time is then presented, which represents a quantum generalisation of the original classical bound. Following this, we review and develop some general principles for the optimisation of thermodynamic processes in the linear-response regime. These include constant speed of control variation according to the thermodynamic metric, absence of quantum coherence, and optimality of small cycles around the point of maximal ratio between heat capacity and relaxation time for Carnot engines.

Transport in one-dimensional integrable quantum systems

These notes are based on a series of three lectures given at the Les Houches summer school on ’Integrability in Atomic and Condensed Matter Physics’ in August 2018. They provide an introduction into the unusual transport properties of integrable models in the linear response regime focussing, in particular, on the spin-1/21/2 XXZ spin chain.

Polymer Brush Bilayers under Stationary Shear Motion at Non-Linear Response Regime: An Impressive Theoretical Approach

The present article addresses the long-standing problem of the polymer brush bilayers under stationary shear ow at non-linear response regime where the system gets a non-Newtonian uid. The main idea behind this research would be the fact that the immense lubricity of the polymer brush bilayers originates from a global restructuring that takes place at large shear rates. It is shown here that physical quantities like, stress tensor, viscosity tensor, the friction coefficient and the chain extensions could become dependent on the shear rate at non-Newtonian regime. Apparently, the sub-linear scaling of the physical quantities at large shear rates is solely due to the fact that the hains stretch in the shear direction.

Polymer brush bilayers under stationary shear motion at linear response regime: A theoretical approach

ABSTRACTStatistical mechanics is employed to tackle the problem of polymer brush bilayers under stationary shear motion. The article addresses, solely, the linear response regime in which the polymer brush bilayers behave very much similar to the Newtonian fluids. My approach to this long-standing problem split drastically from the work already published Kreer, T, Soft Matter, 12, 3479 (2016). It has been thought for many decades that the interpenetration between the brushes is source of the friction between the brush covered surfaces sliding over each other. Whiles, the present article strongly rejects the idea of interpenetration length in that issue. Instead, here, I show that structure of the whole system is significant in friction between brush covered surfaces and the interpenetration is absolutely insignificant. The results of this research would blow one’s mind about how the polymer brush bilayers respond at small shear rates.

The effect of adding side group and changing contact geometry in single pyrene molecular devices

In this study, the thermopower of pyrene molecule in both symmetric and asymmetric junctions to gold electrodes and the role of adding side group have been studied using density functional theory and Green’s function formalism in the linear response regime. We have considered four different configurations and investigated the thermopower property of them. Calculations show that adding electron donating side groups to both symmetrical and anti-symmetrical junction will increase the thermopower. However, the increase is more evident in asymmetric junction. Additionally, the Seebeck coefficient sign is positive which indicates p-type conduction.