title: Controlling the metal-to-insulator relaxation of the metastable hidden quantum state in 1T-TaS2.
abstract: Controllable switching between metastable macroscopic quantum states under nonequilibrium conditions induced either by light or with an external electric field is rapidly becoming of great fundamental interest. We investigate the relaxation properties of a "hidden" (H) charge density wave (CDW) state in thin single crystals of the layered dichalcogenide 1T-TaS2, which can be reached by either a single 35-fs optical laser pulse or an ~30-ps electrical pulse. From measurements of the temperature dependence of the resistivity under different excitation conditions, we find that the metallic H state relaxes to the insulating Mott ground state through a sequence of intermediate metastable states via discrete jumps over a "Devil's staircase." In between the discrete steps, an underlying glassy relaxation process is observed, which arises because of reciprocal-space commensurability frustration between the CDW and the underlying lattice. We show that the metastable state relaxation rate may be externally stabilized by substrate strain, thus opening the way to the design of nonvolatile ultrafast high-temperature memory devices based on switching between CDW states with large intrinsic differences in electrical resistance.
authors.affiliation: Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia. ; Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia.
authors.forename: Igor
authors.initials: I
authors.lastname: Vaskivskyi
authors.affiliation: Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia. ; Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia.
authors.forename: Jan
authors.initials: J
authors.lastname: Gospodaric
authors.affiliation: Laboratory of Theoretical Physics and Statistical Models (LPTMS)-CNRS, UMR 8626, Université Paris-Sud, F-91405 Orsay, France. ; Center of Excellence in Nanoscience and Nanotechnology (CENN) Nanocenter, Jamova 39, SI-1000 Ljubljana, Slovenia.
authors.forename: Serguei
authors.initials: S
authors.lastname: Brazovskii
authors.affiliation: Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
authors.forename: Damjan
authors.initials: D
authors.lastname: Svetin
authors.affiliation: Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
authors.forename: Petra
authors.initials: P
authors.lastname: Sutar
authors.affiliation: Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
authors.forename: Evgeny
authors.initials: E
authors.lastname: Goreshnik
authors.affiliation: Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia. ; Faculty of Electrical Engineering, University of Ljubljana, Tržaška 21, SI-1000 Ljubljana, Slovenia.
authors.forename: Ian A
authors.initials: IA
authors.lastname: Mihailovic
authors.affiliation: Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
authors.forename: Tomaz
authors.initials: T
authors.lastname: Mertelj
authors.affiliation: Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia. ; Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia. ; Center of Excellence in Nanoscience and Nanotechnology (CENN) Nanocenter, Jamova 39, SI-1000 Ljubljana, Slovenia. ; Jožef Stefan International Postgraduate School, Jamova 39, SI-1000 Ljubljana, Slovenia.
authors.forename: Dragan
authors.initials: D
authors.lastname: Mihailovic
keywords: Metastable states; charge density waves; electronic crystals; nonequilibrium relaxation; ultrafast memory devices