Mott transition by an impulsive dielectric breakdown

Abstract

The transition of a Mott insulator to metal, the Mott transition, can occur via carrier doping by elemental substitution, and by photoirradiation, as observed in transition-metal compounds and in organic materials. Here, we show that the application of a strong electric field can induce a Mott transition by a new pathway, namely through impulsive dielectric breakdown. Irradiation of a terahertz electric-field pulse on an ET-based compound, κ-(ET) Cu[N(CN)]Br (ET:bis(ethylenedithio)tetrathiafulvalene), collapses the original Mott gap of ∼30 meV with a ∼0.1 ps time constant after doublon-holon pair productions by quantum tunnelling processes, as indicated by the nonlinear increase of Drude-like low-energy spectral weights. Additionally, we demonstrate metallization using this method is faster than that by a femtosecond laser-pulse irradiation and that the transition dynamics are more electronic and coherent. Thus, strong terahertz-pulse irradiation is an effective approach to achieve a purely electronic Mott transition, enhancing the understanding of its quantum nature.

Nonequilibrium Phase Precursors during a Photoexcited Insulator-to-Metal Transition in V2O3

“…In Mott insulators, the electronic correlations restrict the extent of the electronic wave function to a few nanometers [20,32]. The size of the monoclinic crystallites ξ we determine from X-ray nanoscopy is in agreement with the electronic correlation length ξ el found in bulk V 2 O 3 , Ref.…”

Ultrafast Spin Dynamics in Photodoped Spin-Orbit Mott Insulator Sr2IrO4

“…In our experiment, the initial photoexcited states have a large excess energy as the pump photon energy is much larger than the Mott gap. This might lead to the excitation of other carriers in the J eff ¼ 3=2 band via the impact ionization that subsequently contributes to the changes in reflectivity and magnetization [42,43]. Hence, the decay times seen in our experiment are associated with higher-order scattering processes and can thus be related to the average time necessary to accomplish the processes of the impact ionization.…”

How a dc Electric Field Drives Mott Insulators Out of Equilibrium

“…Photoinduced phase transitions to a nonthermal metal state by 1.55 eV laser pulses have been demonstrated in organic materials, 2,3 a nickel chain compound 4 and in cuprates, 5 while a dielectric breakdown using (quasi-)static fields has recently been observed in Sr 2 CuO 2 , 6 in VO 2 7 and an ET-based compound. 8 These complementary types of field-induced phase transitions have also been studied theoretically in one dimensional models using analytical methods, exact diagonalization and time-dependent density matrix renormalization group calculations, [9][10][11][12][13][14][15][16][17][18] in two dimensional models 9,19 and in higher dimensions using time-dependent Gutzwiller 20 and nonequilibrium dynamical mean field calculations. [21][22][23][24][25][26][27] While these works have provided important insights into the nonequilibrium dynamics of Mott insulators in strong fields, such as the threshold behavior of the field-induced current in the dielectric breakdown case, or the energy distribution of photo-doped carriers after a resonant excitation, we still lack a systematic investigation of the general case where both the field amplitude and driving frequency are of the order of the characteristic energy scales of the system.…”