arXiv subjects

Maxim Dzero

Publications and source records attributed to Maxim Dzero.

60 records · Page 4Linked to original sources

arXiv2009

Topological Kondo Insulators

Kondo insulators are particularly simple type of heavy electron material, where a filled band of heavy quasiparticles gives rise to a narrow band insulator. Starting with the Anderson lattice Hamiltonian, we develop a topological classification of emergent band structures for Kondo insulators and show that these materials may host three-dimensional topological insulating phases. We propose a general and practical prescription of calculating the Z_2 strong and weak topological insulator indices for various lattice structures. Experimental implications of the topological Kondo insulating behavior are discussed.

cond-mat.str-el↗

arXiv2008

Replica theory for fluctuations of the activation barriers in glassy systems

We consider the problem of slow activation dynamics in glassy systems undergoing a random first order phase transition. Using an effective potential approach to supercooled liquids, we determine the spectrum of activation barriers for entropic droplets. We demonstrate that fluctuations of the configurational entropy and of the liquid glass surface tension are crucial to achieve an understanding of the barrier fluctuations in glassy systems and thus are ultimatively responsible for the broad spectrum of excitations and heterogeneous dynamics in glasses. In particular we derive a relation between the length scale for dynamic heterogeneity and the related barrier fluctuations. Diluted entropic droplets are shown to have a Gaussian distribution of barriers, strongly suggesting that non-Gaussian behavior results from droplet-droplet interactions.

cond-mat.dis-nn↗

arXiv2006

Dynamical vanishing of the order parameter in a fermionic condensate

We analyze the dynamics of a condensate of ultra-cold atomic fermions following an abrupt change of the pairing strength. At long times, the system goes to a non-stationary steady state, which we determine exactly. The superfluid order parameter asymptotes to a constant value. We show that the order parameter vanishes when the pairing strength is decreased below a certain critical value. In this case, the steady state of the system combines properties of normal and superfluid states - the gap and the condensate fraction vanish, while the superfluid density is nonzero.

cond-mat.supr-con↗

arXiv2005

Activated events in glasses: the structure of entropic droplets

Using an effective potential approach, we present a replica instanton theory for the dynamics of entropic droplets in glassy systems. Replica symmetry breaking in the droplet interface leads to a length scale dependent reduction of the droplet surface tension and changes the character of the dynamical heterogeneity and activated dynamics in glasses.

cond-mat.dis-nn↗

arXiv2004

Superconductivity in charge Kondo systems

We present a theory of superconductivity in charge Kondo systems, materials with resonant quantum valence fluctuations, in the regime where the transition temperature is comparable to the charge Kondo resonance. We find superconductivity induced by charge Kondo impurities, study how pairing of a superconducting host is enhanced due to charge Kondo centers and investigate the interplay between Kondo-scattering and inter-impurity Josephson coupling. We discuss the implications of our theory for Tl-doped PbTe, which has recently been identified as a candidate charge Kondo system.

cond-mat.str-el↗

arXiv2003

Effects of Density of States Asymmetry on Boundary Resistance of Ferromagnetic-Nonferromagnetic Metal Interface

Asymmetry of conduction of electrons in the spin majority and minority bands of a ferromagnetic metal is well known to produce spin accumulation at the boundary with a normal metal when a current is injected through the interface. However, little emphasis has been put on the density of states (DOS) asymmetry in diffusive ferromagnetic-nonferromagnetic multilayers. We found that if DOS and conduction asymmetry differ, the electric potential in a ferromagnet falls off to its bulk value exponentially on a scale of the spin diffusion length. Therefore the boundary contribution to resistance dramatically depends on whether the potential difference is measured close to the interface or farther than the spin diffusion length from it. This result is not altered by taking surface resistance or spin-flips on the intermetallic boundary into account. Explicit answers for common multilayered spin-valve structures are given.

cond-mat↗