Recently discovered ultrafast transition to the metastable hidden quantum state in 1T-TaS2 attracts a lot of interest due to its potential for practical application as an ultrafast memory. Controlling of the stability of the state is one of the crucial aspects. In the article we investigate relaxation dynamics of the hidden state and propose the ways for its stabilization at higher temperatures.
COBISS.SI-ID: 28753959
In this article we have studied nonequilibrium phase transition into the pseudogap state. The three-pulse experiments have revealed short correlation range of the dynamical state and individual character of the quasiparticle relaxation. Energy required for nonthermal destruction of the pseudogap scales linearly with the gap. This is explained with the model which accounts for subgap phonons generation.
COBISS.SI-ID: 28758311
The superconducting state in one-dimensional nanosystems is very delicate. While fluctuations of the phase of the superconducting wave function lead to the spontaneous decay of persistent supercurrents in thin superconducting wires and nanocircuits, discrete phase-slip fluctuations can also lead to more exotic phenomena, such as the appearance of metastable superconducting states in current-bearing wires. Here we show that switching between different metastable superconducting states in δ-MoN nanowires can be very effectively manipulated by introducing small amplitude electrical noise. Furthermore, we show that deterministic switching between metastable superconducting states with different numbers of phase-slip centres can be achieved in both directions with small electrical current pulse perturbations of appropriate polarity. The observed current-controlled bi-stability is in remarkable agreement with theoretically predicted trajectories of the system switching between different limit cycle solutions of a model one-dimensional superconductor.
COBISS.SI-ID: 29119015
The functionality of computer memory elements is currently based on multi-stability, driven either by locally manipulating the density of electrons in transistors or by switching magnetic or ferroelectric order. Another possibility is switching between metallic and insulating phases by the motion of ions, but their speed is limited by slow nucleation and inhomogeneous percolative growth. Here we demonstrate fast resistance switching in a charge density wave system caused by pulsed current injection. As a charge pulse travels through the material, it converts a commensurately ordered polaronic Mott insulating state in 1T–TaS2 to a metastable electronic state with textured domain walls, accompanied with a conversion of polarons to band states, and concurrent rapid switching from an insulator to a metal. The large resistance change, high switching speed (30 ps) and ultralow energy per bit opens the way to new concepts in non-volatile memory devices manipulating all-electronic states.
COBISS.SI-ID: 29594919
In the last two decades, non-equilibrium spectroscopies have evolved from avant-garde studies to crucial tools for expanding our understanding of the physics of strongly correlated materials. The possibility of obtaining simultaneously spectroscopic and temporal information has led to insights that are complementary to (and in several cases beyond) those attainable by studying the matter at equilibrium. Multiple phase transitions and new orders arising from competing interactions are benchmark examples where the interplay among electrons, lattice, and spin dynamics can be disentangled because of the different timescales that characterize the recovery of the initial ground state. The nature of the broken-symmetry phases and of the bosonic excitations that mediate the electronic interactions, eventually leading to superconductivity or other exotic states, can be revealed by observing the sub-picosecond dynamics of impulsively excited states. Recent experimental developments have made possible to monitor the time-evolution of both the single-particle and collective excitations under extreme conditions, such as those arising from strong and selective photo-stimulation. Here, we review the most recent achievements in the experimental and theoretical studies of the non-equilibrium electronic, optical, structural and magnetic properties of correlated materials. The focus will be mainly on the prototypical case of correlated oxides that exhibit unconventional superconductivity or other exotic phases, even though the discussion will extend also to other topical systems. The necessity of extending the actual experimental capabilities and the numerical and analytic tools to microscopically treat the non-equilibrium phenomena beyond the simple phenomenological approaches represents one of the most challenging new frontier in physics.
COBISS.SI-ID: 29650727