Chemically Induced Nanoscale Josephson Effects in Non-Stoichiometric High-Temperature Superconductors

Abstract

This paper reviews some of the recently suggested (by the author) novel effects expected to occur in intrinsically granular non-stoichiometric material modeled by 2D Josephson junction arrays which are created by a regular 2D network of twin-boundary dislocations with strain fields acting as an insulating barrier between hole-rich domains in underdoped crystals. In Section 2 we consider phase-related magnetization effects, including Josephson chemomagnetism (chemically induced magnetic moment in zero applied magnetic field) and its influence on a low-field magnetization (chemically induced PME), and magnetoconcentration effect (creation of extra oxygen vacancies in applied magnetic field) and its influence on a high-field magnetization (chemically induced analog of "fishtail" anomaly). Section 3 addresses charge-related phenomena which are actually dual to the chemomagnetic effects described in Section 2. More specifically, we discuss a possible existence of a non-zero electric polarization (chemomagnetoelectic effect) and the related change of the charge balance in intrinsically granular non-stoichiometric material under the influence of an applied magnetic field. In particular, we predict an anomalous low-field magnetic behavior of the effective junction charge and concomitant magnetocapacitance in paramagnetic Meissner phase and a charge analog of "fishtail" anomaly at high magnetic fields as well as field-dependent weakening of the chemically-induced Coulomb blockade.