Evidences for local non-centrosymmetricity and strong phonon anomaly in EuCuAs: a Raman spectroscopy and lattice dynamics study.

Phonon modes and their association with the electronic states have been investigated for the metallic EuCuAssystem. In this work, we present the Raman spectra of this pnictide system which clearly shows the presence of seven well defined peaks above 100 cmthat is consistent with the locally non-centrosymmetriccrystal structure, contrary to that what is expected from the accepted symmorphicstructure. Lattice dynamics calculations using thesymmetry attest that there is a commendable agreement between the calculated phonon spectra at the Γ point and the observed Raman mode frequencies, with the most intense peak at∼232 cmbeing ascribed to the A1gmode.

Observation of momentum-dependent charge density wave gap in a layered antiferromagnet [Formula: see text].

Charge density wave (CDW) ordering has been an important topic of study for a long time owing to its connection with other exotic phases such as superconductivity and magnetism. The [Formula: see text] (R = rare-earth elements) family of materials provides a fertile ground to study the dynamics of CDW in van der Waals layered materials, and the presence of magnetism in these materials allows to explore the interplay among CDW and long range magnetic ordering. Here, we have carried out a high-resolution angle-resolved photoemission spectroscopy (ARPES) study of a CDW material [Formula: see text], which is antiferromagnetic below [Formula: see text], along with thermodynamic, electrical transport, magnetic, and Raman measurements.

Theoretical Study of Dynamical and Electronic Properties of Noncentrosymmetric Superconductor NbReSi.

The noncentrosymmetric NbReSi superconductor with Tc≃6.5 K is characterized by the relatively large upper critical magnetic field. Its multigap features were observed experimentally.

Electronic Band Structure and Surface States in Dirac Semimetal LaAgSb.

LaAgSb2 is a Dirac semimetal showing charge density wave (CDW) order. Previous angle-resolved photoemission spectroscopy (ARPES) results suggest the existence of the Dirac-cone-like structure in the vicinity of the Fermi level along the Γ-M direction. This paper is devoted to a complex analysis of the electronic band structure of LaAgSb2 by means of ARPES and theoretical studies within the ab initio method as well as tight binding model formulation.

Electronic properties of BiSe dopped by 3d transition metal (Mn, Fe, Co, or Ni) ions.

Topological insulators are characterized by the existence of band inversion and the possibility of the realization of surface states. Doping with a magnetic atom, which is a source of the time-reversal symmetry breaking, can lead to realization of novel magneto-electronic properties of the system. In this paper, we study effects of substitution by the transition metal ions (Mn, Fe, Co and Ni) into BiSe on its electric properties.

Delocalisation of Majorana quasiparticles in plaquette-nanowire hybrid system.

Interplay between superconductivity, spin-orbit coupling and magnetic field can lead to realisation of the topologically non-trivial states which in finite one dimensional nanowires are manifested by emergence of a pair of zero-energy Majorana bound states. On the other hand, in two dimensional systems the chiral edge states can appear. We investigate novel properties of the bound states in a system of mixed dimensionality, composed of one-dimensional nanowire connected with two-dimensional plaquette.

Phase separations induced by a trapping potential in one-dimensional fermionic systems as a source of core-shell structures.

Ultracold fermionic gases in optical lattices give a great opportunity for creating different types of novel states. One of them is phase separation induced by a trapping potential between different types of superfluid phases. The core-shell structures, occurring in systems with a trapping potential, are a good example of such separations.

Electrostatic formation of the Majorana quasiparticles in the quantum dot-nanoring structure.

Zero-energy Majorana quasiparticles can be induced at the edges of low dimensional systems. Non-Abelian statistics of these states make them valid candidates for the realisation of topological quantum computer. From the practical point of view, it is crucial to obtain a system in which an on demand creation and manipulation of this type of bound states is feasible.

Quantum engineering of Majorana quasiparticles in one-dimensional optical lattices.

We propose a feasible way of engineering Majorana-type quasiparticles in ultracold fermionic gases on a one-dimensional (1D) optical lattice. For this purpose, imbalanced ultracold atoms interacting by the spin-orbit coupling should be hybridized with a three-dimensional Bose-Einstein condensate molecular cloud. We show that the Majorana-type excitations can be created or annihilated upon constraining the profile of a trapping potential and/or an internal scattering barier.

Interplay between pairing and correlations in spin-polarized bound states.

We investigate single and multiple defects embedded in a superconducting host, studying the interplay between the proximity-induced pairing and interactions. We explore the influence of the spin-orbit coupling on energies, polarization and spatial patterns of the bound (Yu-Shiba-Rusinov) states of magnetic impurities in a two-dimensional square lattice. We also address the peculiar bound states in the proximitized Rashba chain, resembling the Majorana quasiparticles, focusing on their magnetic polarization that has been recently reported by S.

Diversity of charge orderings in correlated systems.

The phenomenon associated with inhomogeneous distribution of electron density is known as a charge ordering. In this work, we study the zero-bandwidth limit of the extended Hubbard model, which can be considered as a simple effective model of charge ordered insulators. It consists of the on-site interaction U and the intersite density-density interactions W_{1} and W_{2} between nearest neighbors and next-nearest neighbors, respectively.

Influence of the orbital effects on the Majorana quasi-particles in a nanowire.

Majorana quasi-particles can be realised using magnetic field in the form of diamagnetic (orbital) or paramagnetic effects. In both cases, the magnetic field induces a topologically non-trivial phase of matter. In this paper, the influence of orbital effects on Majorana bound states induced by paramagnetic effects in 1D nanowire is elaborated.

The influence of the dimensionality of the system on the realization of unconventional Fulde-Ferrell-Larkin-Ovchinnikov pairing in ultra-cold Fermi gases.

The recent development of experimental techniques in ultracold atomic Fermi gases is extremely helpful in the progress of the realization of the unconventional Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluid phase in quasi-one dimensional systems (Liao et al 2010 Nature 467 567). Due to a Fermi surface nesting, which is enhanced in 1D, the low-dimensional systems are particularly good candidates to find the FFLO phase stable. We investigate the influence of a dimensional crossover (from one dimension (1D) to two dimensions (2D) or three dimensions (3D)) on the stability of the FFLO state in the spin-imbalanced attractive Hubbard model.

Magnetic Lifshitz transition and its consequences in multi-band iron-based superconductors.

In this paper we address Lifshitz transition induced by applied external magnetic field in a case of iron-based superconductors, in which a difference between the Fermi level and the edges of the bands is relatively small. We introduce and investigate a two-band model with intra-band pairing in the relevant parameters regime to address a generic behaviour of a system with hole-like and electron-like bands in external magnetic field. Our results show that two Lifshitz transitions can develop in analysed systems and the first one occurs in the superconducting phase and takes place at approximately constant magnetic field.

Multiple phase transitions in Pauli-limited iron-based superconductors.

Specific heat measurements have been successfully used to probe unconventional superconducting phases in one-band heavy-fermion and organic superconductors. We extend the method to study successive phase transitions in multi-band materials such as iron-based superconductors. The signatures are multiple peaks in the specific heat, at low temperatures and high magnetic field, which can lead to the experimental verification of unconventional superconducting states with non-zero total momentum.

The Fulde-Ferrell-Larkin-Ovchinnikov phase in the presence of pair hopping interaction.

The recent experimental support for the presence of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase in CeCoIn(5) directed attention towards the mechanisms responsible for this type of superconductivity. We investigate the FFLO state in a model where on-site/inter-site pairing coexists with the repulsive pair hopping interaction. The latter interaction is interesting in that it leads to pairing with non-zero momentum of the Cooper pairs even in the absence of the external magnetic field (the so-called η pairing).