Ramp-Reversal Memory and Phase-Boundary Scarring in Transition Metal Oxides.
Transition metal oxides are complex electronic systems that exhibit a multitude of collective phenomena. Two archetypal examples are VO2and NdNiO3, which undergo a metal-insulator phase transition (MIT), the origin of which is still under debate. Here this study reports the discovery of a memory effect in both systems, manifested through an increase of resistance at a specific temperature, which is set by reversing the temperature ramp from heating to cooling during the MIT. The characteristics of this ramp-reversal memory effect do not coincide with any previously reported history or memory effects in manganites, electron-glass or magnetic systems. From a broad range of experimental features, supported by theoretical modelling, it is found that the main ingredients for the effect to arise are the spatial phase separation of metallic and insulating regions during the MIT and the coupling of lattice strain to the local transition temperature of the phase transition. We conclude that the emergent memory effect originates from phase boundaries at the reversal temperature leaving "scars" in the underlying lattice structure, giving rise to a local increase in the transition temperature. The universality and robustness of the effect shed new light on the MIT in complex oxides.
Department of Physics, Bar Ilan University, Ramat-Gan, IL, 5290002, Israel.|Bar-Ilan Institute of Nanotechnology and Advanced Materials, Ramat-Gan, IL, 5290002, Israel.
Naor
N
Vardi
Department of Physics, Bar Ilan University, Ramat-Gan, IL, 5290002, Israel.|Bar-Ilan Institute of Nanotechnology and Advanced Materials, Ramat-Gan, IL, 5290002, Israel.
Elihu
E
Anouchi
Department of Physics, Bar Ilan University, Ramat-Gan, IL, 5290002, Israel.|Bar-Ilan Institute of Nanotechnology and Advanced Materials, Ramat-Gan, IL, 5290002, Israel.
Tony
T
Yamin
Department of Physics, University of Arkansas, Fayetteville, AR, 72701, USA.
Srimanta
S
Middey
Department of Physics, University of Arkansas, Fayetteville, AR, 72701, USA.
Michael
M
Kareev
Department of Physics, University of Arkansas, Fayetteville, AR, 72701, USA.
Jak
J
Chakhalian
Department of Chemistry, Ben Gurion University, Be'er Sheva, IL, 841050, Israel.|Ilse-Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Be'er Sheva, IL, 8410501, Israel.
Yonatan
Y
Dubi
Department of Physics, Bar Ilan University, Ramat-Gan, IL, 5290002, Israel.|Bar-Ilan Institute of Nanotechnology and Advanced Materials, Ramat-Gan, IL, 5290002, Israel.
Amos
A
Sharoni
emergent phenomena; memory devices; metal insulator transition; transition metal oxides; transport properties