How a dc Electric Field Drives Mott Insulators Out of Equilibrium

Abstract

Out of equilibrium phenomena are a major issue of modern physics. In particular, correlated materials such as Mott insulators experience fascinating long-lived exotic states under a strong electric field. Yet, the origin of their destabilization by the electric field is not elucidated. Here we present a comprehensive study of the electrical response of canonical Mott insulators GaM_{4}Q_{8} (M=V, Nb, Ta, Mo; Q=S, Se) in the context of a microscopic theory of electrical breakdown where in-gap states allow for a description in terms of a two-temperature model. Our results show how the nonlinearities and the resistive transition originate from a massive creation of hot electrons under an electric field. These results give new insights for the control of the long-lived states reached under an electric field in these systems which has recently open the way to new functionalities used in neuromorphic applications.

Non-thermal resistive switching in Mott insulator nanowires

“…In materials where the IMT takes place as a function of temperature, such as VO 2 and V 2 O 3 , Joule heating due to current flow is an obvious candidate for triggering the transition. It has been argued, however, that the electric field applied in this process may induce the IMT non-thermally, without heating the material to its IMT temperature (T IMT ) [21][22][23][24][25][26][27] . Despite many studies, the switching mechanism is not yet understood.…”

“…Despite many studies, the switching mechanism is not yet understood. Even for the same materials, in some cases Joule heating is invoked, while in others non-thermal effects of the electric field may play an important role [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] . In a few studies, field-assisted carrier generation has been invoked as a possible driving mechanism for this non-thermal IMT, but no clear evidence linking the two phenomena was shown.…”

THz Driven Dynamics in Mott Insulator GaTa4 Se8

“…We present our results on THz driven dynamics in bulk GaTa4Se8, a Mott insulator which exhibits clear electric Mott transitions. At atmospheric pressure the paramagnetic Mott insulator phase of GaTa4Se8 extends roughly between 55 K and 150 K [1], followed at higher temperatures by a smooth crossover into a "bad Mott" region where the gap is progressively filled by transferred incoherent spectral weight [2]. As shown in Fig.…”

“…In these compounds, an abrupt drop of electrical resistivity is observed under the application of electric fields for a few tens of microseconds. This occurs only for fields above a typical 1 -10 kV/cm threshold [1]. Such electric Mott transitions are volatile for fields just above threshold but become non-volatile under larger electric fields, which is very promising for possible applications in e.g.…”

Millimeter- and Terahertz-wave stochastic sensors based on reversible insulator-to-metal transition in vanadium dioxide

“…Formation of conducting filaments at bias voltages above a threshold is explained in some studies 22 , while the mechanism of filamentation has been differently interpreted, such as the non-uniform current distribution followed by local Joule heating [22][23][24] , or a breakdown mechanism similar to the one in thin oxides 25 . On the other hand, it has been argued that the electric field can induce IMT through nucleation of conducting filaments similar to the mechanism in chalcogenide-based phase-change memory and switches 26 or without the need for a thermal process in Mott insulators [27][28][29] . The physics of such transitions is still under debate but it is recognized that it involves nucleation processes related to conductive path formation that are stochastic in nature 30 .…”