Cooperative dynamics in charge-ordered state ofα-(BEDT-TTF)2I3

Abstract

Electric-field-dependent pulse measurements are reported in the charge-ordered state of α-(BEDT-TTF)2I3. At low electric fields up to about 50 V/cm only negligible deviations from Ohmic behavior can be identified with no threshold field. At larger electric fields and up to about 100 V/cm a reproducible negative differential resistance is observed with a significant change in shape of the measured resistivity in time. These changes critically depend whether constant voltage or constant current is applied to the single crystal. At high enough electric fields the resistance displays a dramatic drop down to metallic values and relaxes subsequently in a single-exponential manner to its low-field steady-state value. We argue that such an electric-field induced negative differential resistance and switching to transient states are fingerprints of cooperative domain-wall dynamics inherent to two-dimensional bond-charge density wave with ferroelectric-like nature.

Electrically induced phase transition inα−(BEDT-TTF)2I3: Indications for Dirac-like hot charge carriers

“…Eventually all energy is stored in the lattice subsystem; without any influx the temperature rises leading to a linear drop of the reflected signal. This picture consistently explains also our electric pump-probe experiments 21 where the resistivity recovers in an exponential manner within a few milliseconds after the highly conducting state was initialized by a 3 ms long voltage pulse. (4) The linear decrease in ∆ t R(ν, t) after 17 ms can be quantitatively described by Newton's law of cooling Q cool = −λ therm (T L − T 0 ), with λ therm is the thermal conductivity, T 0 denoting the environment temperature, and T L the temperature of the heated lattice.…”

“…Since its discovery three decades ago, the intererst in the title compound never faded because it exhibits a rich temperature-pressure phase diagram, with a number of intriguing quantum phenomena ranging from electronic ferroelectricity [15][16][17] to superconductivity, 18,19 from nonlinear transport 20,21 to zero-gap semiconductivity 22,23 characterized by Dirac cones and massless Dirac fermions, [24][25][26][27] but also the appearance of persistent photoconduction, 28 photoinduced phase transition, [29][30][31] and nonlinear ultrafast optical response.…”

“…21 Note that at reduced temperatures the electric field must be significantly increased to induce the high conducting state. It should also be pointed out that despite the different absolute values of resistivity recorded, the step height between low-and highconducting range is again about two orders of magnitude, as in the case of T = 125 K.…”

Light-Induced Current Oscillations in the Charge-Ordered State of (TMTTF)2SbF6

“…4. Current oscillations occur frequently in nonlinear transport studies in various organic conductors [37,[65][66][67][68][69][70]. There, they are often related to sliding charge-density waves (CDW) or electrically induced insulator-metal transitions accompanied by a bistability [46,65].…”

Spin excitations in the quasi-two-dimensional charge-ordered insulatorα−(BEDT−TTF)2I3probed viaIshikawa1, Hirata2, Liu3 et al. 2016Phys. Rev. B

“…However, the presence of the low-energy linear spectrum near EF is hidden at low T beneath the first-order chargeordering (CO) transition taking place at TCO ≈ 135K [1,3,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] due to strong electron correlations [28,29]. The transition is accompanied by an opening of an energy gap in the charge and spin excitation spectra and a formation of quasi-one-dimensional (quasi-1D) charge stripes along the crystalline b axis [14], leading to an insulating spin-singlet ground state [1,3,17,18,20,30,31]. The inversion centers, locating on the molecules B and C and in between the molecules A and A' at T > TCO [ Fig.…”