Special Issue "New Insights into Metal–Insulator Transitions"

Dear Colleagues,

Metal–insulator transitions (MITs) are one of the most important phenomena in condensed-matter physics. They connect two opposite boundaries: the metallic, where elementary excitations are single particles of a fermionic nature, and insulating, where elementary excitations are collective of a bosonic nature. Near the transition, both types of excitations coexist, which greatly complicates the problem from the theoretical side; thus, it is not surprising that its understanding is still incomplete, even after over 70 years of intensive research. There are various mechanisms that drive MITs through the localization of conducting electrons, most common ones being the Mott–Hubbard (caused by an electron–electron correlation), Anderson (caused by a disorder) and Peierls (caused by electron–phonon interactions) mechanisms. Some novel insights in these phenomena investigated the interplay between different mechanisms, and an especially interesting one is the complex theory of the Mott–Anderson localization, where both electron correlation and disorder cause electron localization. Additionally, interesting is the influence of electron localization on the magnetic degrees of freedom and the connection with spin liquids.

MITs have been observed in a variety of materials, with various exotic insulating ground states, including different charge and spin orderings, density waves, Mott insulators, etc. Additionally, interesting is the conducting side of MITs, where deviations from conventional Fermi liquid are often found. The transition between different states can be driven by a change in temperature, pressure, magnetic field, chemical substitution or doping. One of the most intriguing phenomena is colossal magnetoresistance (CMR), observed in manganites, where resistivity changes by several orders of magnitude with the application of a magnetic field, something which is still not fully understood, but that has been attributed to nanoscale phase separation.

The aim of this Special Issue is to report on novel experimental and theoretical findings regarding MITs and related intriguing phenomena, with the potential possibly of ascertaining numerous novel questions and future directions.

Prof. Dr. Emil Tafra
Dr. Matija Čulo
Guest Editors

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• metal–insulator transition
• correlated electron systems
• Mott localization
• Anderson localization
• Hubbard model
• hopping conductivity
• transport properties
• dielectric properties
• magnetic properties
• optical properties
• quantum spin liquids
• charge order
• organic conductors
• manganites
• cuprates